Mechanical conversion to use prefixcmp()

This mechanically converts strncmp() to use prefixcmp(), but only when
the parameters match specific patterns, so that they can be verified
easily.  Leftover from this will be fixed in a separate step, including
idiotic conversions like

    if (!strncmp("foo", arg, 3))

  =>

    if (!(-prefixcmp(arg, "foo")))

This was done by using this script in px.perl

   #!/usr/bin/perl -i.bak -p
   if (/strncmp\(([^,]+), "([^\\"]*)", (\d+)\)/ && (length($2) == $3)) {
           s|strncmp\(([^,]+), "([^\\"]*)", (\d+)\)|prefixcmp($1, "$2")|;
   }
   if (/strncmp\("([^\\"]*)", ([^,]+), (\d+)\)/ && (length($1) == $3)) {
           s|strncmp\("([^\\"]*)", ([^,]+), (\d+)\)|(-prefixcmp($2, "$1"))|;
   }

and running:

   $ git grep -l strncmp -- '*.c' | xargs perl px.perl

Signed-off-by: Junio C Hamano <junkio@cox.net>

48 files changed, 211 insertions, 211 deletions

diff --git a/builtin-apply.c b/builtin-apply.c
index abe353871..d67817834 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -1129,11 +1129,11 @@ static struct fragment *parse_binary_hunk(char **buf_p,
 
 	*status_p = 0;
 
-	if (!strncmp(buffer, "delta ", 6)) {
+	if (!prefixcmp(buffer, "delta ")) {
 		patch_method = BINARY_DELTA_DEFLATED;
 		origlen = strtoul(buffer + 6, NULL, 10);
 	}
-	else if (!strncmp(buffer, "literal ", 8)) {
+	else if (!prefixcmp(buffer, "literal ")) {
 		patch_method = BINARY_LITERAL_DEFLATED;
 		origlen = strtoul(buffer + 8, NULL, 10);
 	}
@@ -2608,14 +2608,14 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 			read_stdin = 0;
 			continue;
 		}
-		if (!strncmp(arg, "--exclude=", 10)) {
+		if (!prefixcmp(arg, "--exclude=")) {
 			struct excludes *x = xmalloc(sizeof(*x));
 			x->path = arg + 10;
 			x->next = excludes;
 			excludes = x;
 			continue;
 		}
-		if (!strncmp(arg, "-p", 2)) {
+		if (!prefixcmp(arg, "-p")) {
 			p_value = atoi(arg + 2);
 			continue;
 		}
@@ -2669,13 +2669,13 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 			line_termination = 0;
 			continue;
 		}
-		if (!strncmp(arg, "-C", 2)) {
+		if (!prefixcmp(arg, "-C")) {
 			p_context = strtoul(arg + 2, &end, 0);
 			if (*end != '\0')
 				die("unrecognized context count '%s'", arg + 2);
 			continue;
 		}
-		if (!strncmp(arg, "--whitespace=", 13)) {
+		if (!prefixcmp(arg, "--whitespace=")) {
 			whitespace_option = arg + 13;
 			parse_whitespace_option(arg + 13);
 			continue;
diff --git a/builtin-archive.c b/builtin-archive.c
index f613ac251..0c56de069 100644
--- a/builtin-archive.c
+++ b/builtin-archive.c
@@ -35,7 +35,7 @@ static int run_remote_archiver(const char *remote, int argc,
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
-		if (!strncmp("--exec=", arg, 7)) {
+		if (!(-prefixcmp(arg, "--exec="))) {
 			if (exec_at)
 				die("multiple --exec specified");
 			exec = arg + 7;
@@ -62,7 +62,7 @@ static int run_remote_archiver(const char *remote, int argc,
 	if (buf[len-1] == '\n')
 		buf[--len] = 0;
 	if (strcmp(buf, "ACK")) {
-		if (len > 5 && !strncmp(buf, "NACK ", 5))
+		if (len > 5 && !prefixcmp(buf, "NACK "))
 			die("git-archive: NACK %s", buf + 5);
 		die("git-archive: protocol error");
 	}
@@ -166,11 +166,11 @@ int parse_archive_args(int argc, const char **argv, struct archiver *ar)
 			verbose = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--format=", 9)) {
+		if (!prefixcmp(arg, "--format=")) {
 			format = arg + 9;
 			continue;
 		}
-		if (!strncmp(arg, "--prefix=", 9)) {
+		if (!prefixcmp(arg, "--prefix=")) {
 			base = arg + 9;
 			continue;
 		}
@@ -218,7 +218,7 @@ static const char *extract_remote_arg(int *ac, const char **av)
 		if (!strcmp(arg, "--"))
 			no_more_options = 1;
 		if (!no_more_options) {
-			if (!strncmp(arg, "--remote=", 9)) {
+			if (!prefixcmp(arg, "--remote=")) {
 				if (remote)
 					die("Multiple --remote specified");
 				remote = arg + 9;
diff --git a/builtin-blame.c b/builtin-blame.c
index 5669a169f..db311bfba 100644
--- a/builtin-blame.c
+++ b/builtin-blame.c
@@ -2097,17 +2097,17 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 			output_option |= OUTPUT_LONG_OBJECT_NAME;
 		else if (!strcmp("-S", arg) && ++i < argc)
 			revs_file = argv[i];
-		else if (!strncmp("-M", arg, 2)) {
+		else if (!(-prefixcmp(arg, "-M"))) {
 			opt |= PICKAXE_BLAME_MOVE;
 			blame_move_score = parse_score(arg+2);
 		}
-		else if (!strncmp("-C", arg, 2)) {
+		else if (!(-prefixcmp(arg, "-C"))) {
 			if (opt & PICKAXE_BLAME_COPY)
 				opt |= PICKAXE_BLAME_COPY_HARDER;
 			opt |= PICKAXE_BLAME_COPY | PICKAXE_BLAME_MOVE;
 			blame_copy_score = parse_score(arg+2);
 		}
-		else if (!strncmp("-L", arg, 2)) {
+		else if (!(-prefixcmp(arg, "-L"))) {
 			if (!arg[2]) {
 				if (++i >= argc)
 					usage(blame_usage);
diff --git a/builtin-branch.c b/builtin-branch.c
index d0e720936..d0179b00a 100644
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -59,7 +59,7 @@ int git_branch_config(const char *var, const char *value)
 		branch_use_color = git_config_colorbool(var, value);
 		return 0;
 	}
-	if (!strncmp(var, "color.branch.", 13)) {
+	if (!prefixcmp(var, "color.branch.")) {
 		int slot = parse_branch_color_slot(var, 13);
 		color_parse(value, var, branch_colors[slot]);
 		return 0;
@@ -178,13 +178,13 @@ static int append_ref(const char *refname, const unsigned char *sha1, int flags,
 	int len;
 
 	/* Detect kind */
-	if (!strncmp(refname, "refs/heads/", 11)) {
+	if (!prefixcmp(refname, "refs/heads/")) {
 		kind = REF_LOCAL_BRANCH;
 		refname += 11;
-	} else if (!strncmp(refname, "refs/remotes/", 13)) {
+	} else if (!prefixcmp(refname, "refs/remotes/")) {
 		kind = REF_REMOTE_BRANCH;
 		refname += 13;
-	} else if (!strncmp(refname, "refs/tags/", 10)) {
+	} else if (!prefixcmp(refname, "refs/tags/")) {
 		kind = REF_TAG;
 		refname += 10;
 	}
@@ -446,7 +446,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 			reflog = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--abbrev=", 9)) {
+		if (!prefixcmp(arg, "--abbrev=")) {
 			abbrev = atoi(arg+9);
 			continue;
 		}
@@ -476,7 +476,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		detached = 1;
 	}
 	else {
-		if (strncmp(head, "refs/heads/", 11))
+		if (prefixcmp(head, "refs/heads/"))
 			die("HEAD not found below refs/heads!");
 		head += 11;
 	}
diff --git a/builtin-checkout-index.c b/builtin-checkout-index.c
index b097c888a..afe4b0e45 100644
--- a/builtin-checkout-index.c
+++ b/builtin-checkout-index.c
@@ -223,12 +223,12 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 			to_tempfile = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--prefix=", 9)) {
+		if (!prefixcmp(arg, "--prefix=")) {
 			state.base_dir = arg+9;
 			state.base_dir_len = strlen(state.base_dir);
 			continue;
 		}
-		if (!strncmp(arg, "--stage=", 8)) {
+		if (!prefixcmp(arg, "--stage=")) {
 			if (!strcmp(arg + 8, "all")) {
 				to_tempfile = 1;
 				checkout_stage = CHECKOUT_ALL;
diff --git a/builtin-describe.c b/builtin-describe.c
index bcc645622..165917e40 100644
--- a/builtin-describe.c
+++ b/builtin-describe.c
@@ -52,7 +52,7 @@ static int get_name(const char *path, const unsigned char *sha1, int flag, void
 	 * If --tags, then any tags are used.
 	 * Otherwise only annotated tags are used.
 	 */
-	if (!strncmp(path, "refs/tags/", 10)) {
+	if (!prefixcmp(path, "refs/tags/")) {
 		if (object->type == OBJ_TAG)
 			prio = 2;
 		else
@@ -254,12 +254,12 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			all = 1;
 		else if (!strcmp(arg, "--tags"))
 			tags = 1;
-		else if (!strncmp(arg, "--abbrev=", 9)) {
+		else if (!prefixcmp(arg, "--abbrev=")) {
 			abbrev = strtoul(arg + 9, NULL, 10);
 			if (abbrev != 0 && (abbrev < MINIMUM_ABBREV || 40 < abbrev))
 				abbrev = DEFAULT_ABBREV;
 		}
-		else if (!strncmp(arg, "--candidates=", 13)) {
+		else if (!prefixcmp(arg, "--candidates=")) {
 			max_candidates = strtoul(arg + 13, NULL, 10);
 			if (max_candidates < 1)
 				max_candidates = 1;
diff --git a/builtin-fmt-merge-msg.c b/builtin-fmt-merge-msg.c
index 87d3d63ec..148988356 100644
--- a/builtin-fmt-merge-msg.c
+++ b/builtin-fmt-merge-msg.c
@@ -81,7 +81,7 @@ static int handle_line(char *line)
 	if (len < 43 || line[40] != '\t')
 		return 1;
 
-	if (!strncmp(line + 41, "not-for-merge", 13))
+	if (!prefixcmp(line + 41, "not-for-merge"))
 		return 0;
 
 	if (line[41] != '\t')
@@ -119,15 +119,15 @@ static int handle_line(char *line)
 	if (pulling_head) {
 		origin = xstrdup(src);
 		src_data->head_status |= 1;
-	} else if (!strncmp(line, "branch ", 7)) {
+	} else if (!prefixcmp(line, "branch ")) {
 		origin = xstrdup(line + 7);
 		append_to_list(&src_data->branch, origin, NULL);
 		src_data->head_status |= 2;
-	} else if (!strncmp(line, "tag ", 4)) {
+	} else if (!prefixcmp(line, "tag ")) {
 		origin = line;
 		append_to_list(&src_data->tag, xstrdup(origin + 4), NULL);
 		src_data->head_status |= 2;
-	} else if (!strncmp(line, "remote branch ", 14)) {
+	} else if (!prefixcmp(line, "remote branch ")) {
 		origin = xstrdup(line + 14);
 		append_to_list(&src_data->r_branch, origin, NULL);
 		src_data->head_status |= 2;
@@ -280,7 +280,7 @@ int cmd_fmt_merge_msg(int argc, const char **argv, const char *prefix)
 	current_branch = resolve_ref("HEAD", head_sha1, 1, NULL);
 	if (!current_branch)
 		die("No current branch");
-	if (!strncmp(current_branch, "refs/heads/", 11))
+	if (!prefixcmp(current_branch, "refs/heads/"))
 		current_branch += 11;
 
 	while (fgets(line, sizeof(line), in)) {
diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index 16c785f04..ac0b9f608 100644
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -814,7 +814,7 @@ int cmd_for_each_ref(int ac, const char **av, char *prefix)
 			i++;
 			break;
 		}
-		if (!strncmp(arg, "--format=", 9)) {
+		if (!prefixcmp(arg, "--format=")) {
 			if (format)
 				die("more than one --format?");
 			format = arg + 9;
@@ -844,7 +844,7 @@ int cmd_for_each_ref(int ac, const char **av, char *prefix)
 			quote_style = QUOTE_TCL;
 			continue;
 		}
-		if (!strncmp(arg, "--count=", 8)) {
+		if (!prefixcmp(arg, "--count=")) {
 			if (maxcount)
 				die("more than one --count?");
 			maxcount = atoi(arg + 8);
@@ -852,7 +852,7 @@ int cmd_for_each_ref(int ac, const char **av, char *prefix)
 				die("The number %s did not parse", arg);
 			continue;
 		}
-		if (!strncmp(arg, "--sort=", 7)) {
+		if (!prefixcmp(arg, "--sort=")) {
 			struct ref_sort *s = xcalloc(1, sizeof(*s));
 			int len;
 
diff --git a/builtin-fsck.c b/builtin-fsck.c
index 6da3814d5..6abf498d2 100644
--- a/builtin-fsck.c
+++ b/builtin-fsck.c
@@ -546,7 +546,7 @@ static int fsck_head_link(void)
 
 	if (!head_points_at || !(flag & REF_ISSYMREF))
 		return error("HEAD is not a symbolic ref");
-	if (strncmp(head_points_at, "refs/heads/", 11))
+	if (prefixcmp(head_points_at, "refs/heads/"))
 		return error("HEAD points to something strange (%s)",
 			     head_points_at);
 	if (is_null_sha1(sha1))
diff --git a/builtin-grep.c b/builtin-grep.c
index 2bfbdb714..cec22047c 100644
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -527,9 +527,9 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			opt.word_regexp = 1;
 			continue;
 		}
-		if (!strncmp("-A", arg, 2) ||
-		    !strncmp("-B", arg, 2) ||
-		    !strncmp("-C", arg, 2) ||
+		if (!(-prefixcmp(arg, "-A")) ||
+		    !(-prefixcmp(arg, "-B")) ||
+		    !(-prefixcmp(arg, "-C")) ||
 		    (arg[0] == '-' && '1' <= arg[1] && arg[1] <= '9')) {
 			unsigned num;
 			const char *scan;
diff --git a/builtin-init-db.c b/builtin-init-db.c
index 12e43d0db..4df9fd0fa 100644
--- a/builtin-init-db.c
+++ b/builtin-init-db.c
@@ -283,11 +283,11 @@ int cmd_init_db(int argc, const char **argv, const char *prefix)
 
 	for (i = 1; i < argc; i++, argv++) {
 		const char *arg = argv[1];
-		if (!strncmp(arg, "--template=", 11))
+		if (!prefixcmp(arg, "--template="))
 			template_dir = arg+11;
 		else if (!strcmp(arg, "--shared"))
 			shared_repository = PERM_GROUP;
-		else if (!strncmp(arg, "--shared=", 9))
+		else if (!prefixcmp(arg, "--shared="))
 			shared_repository = git_config_perm("arg", arg+9);
 		else
 			usage(init_db_usage);
diff --git a/builtin-log.c b/builtin-log.c
index af2de5437..ad1e8c054 100644
--- a/builtin-log.c
+++ b/builtin-log.c
@@ -32,7 +32,7 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 		rev->always_show_header = 0;
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
-		if (!strncmp(arg, "--encoding=", 11)) {
+		if (!prefixcmp(arg, "--encoding=")) {
 			arg += 11;
 			if (strcmp(arg, "none"))
 				git_log_output_encoding = strdup(arg);
@@ -287,7 +287,7 @@ static void reopen_stdout(struct commit *commit, int nr, int keep_subject)
 
 		sol += 2;
 		/* strip [PATCH] or [PATCH blabla] */
-		if (!keep_subject && !strncmp(sol, "[PATCH", 6)) {
+		if (!keep_subject && !prefixcmp(sol, "[PATCH")) {
 			char *eos = strchr(sol + 6, ']');
 			if (eos) {
 				while (isspace(*eos))
@@ -435,7 +435,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		else if (!strcmp(argv[i], "-n") ||
 				!strcmp(argv[i], "--numbered"))
 			numbered = 1;
-		else if (!strncmp(argv[i], "--start-number=", 15))
+		else if (!prefixcmp(argv[i], "--start-number="))
 			start_number = strtol(argv[i] + 15, NULL, 10);
 		else if (!strcmp(argv[i], "--start-number")) {
 			i++;
@@ -471,13 +471,13 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		}
 		else if (!strcmp(argv[i], "--attach"))
 			rev.mime_boundary = git_version_string;
-		else if (!strncmp(argv[i], "--attach=", 9))
+		else if (!prefixcmp(argv[i], "--attach="))
 			rev.mime_boundary = argv[i] + 9;
 		else if (!strcmp(argv[i], "--ignore-if-in-upstream"))
 			ignore_if_in_upstream = 1;
 		else if (!strcmp(argv[i], "--thread"))
 			thread = 1;
-		else if (!strncmp(argv[i], "--in-reply-to=", 14))
+		else if (!prefixcmp(argv[i], "--in-reply-to="))
 			in_reply_to = argv[i] + 14;
 		else if (!strcmp(argv[i], "--in-reply-to")) {
 			i++;
@@ -485,7 +485,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 				die("Need a Message-Id for --in-reply-to");
 			in_reply_to = argv[i];
 		}
-		else if (!strncmp(argv[i], "--suffix=", 9))
+		else if (!prefixcmp(argv[i], "--suffix="))
 			fmt_patch_suffix = argv[i] + 9;
 		else
 			argv[j++] = argv[i];
diff --git a/builtin-ls-files.c b/builtin-ls-files.c
index ac89eb2f7..4e1d5af63 100644
--- a/builtin-ls-files.c
+++ b/builtin-ls-files.c
@@ -406,7 +406,7 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 			add_exclude(argv[++i], "", 0, &dir.exclude_list[EXC_CMDL]);
 			continue;
 		}
-		if (!strncmp(arg, "--exclude=", 10)) {
+		if (!prefixcmp(arg, "--exclude=")) {
 			exc_given = 1;
 			add_exclude(arg+10, "", 0, &dir.exclude_list[EXC_CMDL]);
 			continue;
@@ -416,12 +416,12 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 			add_excludes_from_file(&dir, argv[++i]);
 			continue;
 		}
-		if (!strncmp(arg, "--exclude-from=", 15)) {
+		if (!prefixcmp(arg, "--exclude-from=")) {
 			exc_given = 1;
 			add_excludes_from_file(&dir, arg+15);
 			continue;
 		}
-		if (!strncmp(arg, "--exclude-per-directory=", 24)) {
+		if (!prefixcmp(arg, "--exclude-per-directory=")) {
 			exc_given = 1;
 			dir.exclude_per_dir = arg + 24;
 			continue;
@@ -434,7 +434,7 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 			error_unmatch = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--abbrev=", 9)) {
+		if (!prefixcmp(arg, "--abbrev=")) {
 			abbrev = strtoul(arg+9, NULL, 10);
 			if (abbrev && abbrev < MINIMUM_ABBREV)
 				abbrev = MINIMUM_ABBREV;
diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 583da38b6..6ee6b0b26 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -811,7 +811,7 @@ int cmd_mailinfo(int argc, const char **argv, const char *prefix)
 			metainfo_charset = def_charset;
 		else if (!strcmp(argv[1], "-n"))
 			metainfo_charset = NULL;
-		else if (!strncmp(argv[1], "--encoding=", 11))
+		else if (!prefixcmp(argv[1], "--encoding="))
 			metainfo_charset = argv[1] + 11;
 		else
 			usage(mailinfo_usage);
diff --git a/builtin-name-rev.c b/builtin-name-rev.c
index 36f1ba6d3..2c3d14c1b 100644
--- a/builtin-name-rev.c
+++ b/builtin-name-rev.c
@@ -85,7 +85,7 @@ static int name_ref(const char *path, const unsigned char *sha1, int flags, void
 	struct name_ref_data *data = cb_data;
 	int deref = 0;
 
-	if (data->tags_only && strncmp(path, "refs/tags/", 10))
+	if (data->tags_only && prefixcmp(path, "refs/tags/"))
 		return 0;
 
 	if (data->ref_filter && fnmatch(data->ref_filter, path, 0))
@@ -101,9 +101,9 @@ static int name_ref(const char *path, const unsigned char *sha1, int flags, void
 	if (o && o->type == OBJ_COMMIT) {
 		struct commit *commit = (struct commit *)o;
 
-		if (!strncmp(path, "refs/heads/", 11))
+		if (!prefixcmp(path, "refs/heads/"))
 			path = path + 11;
-		else if (!strncmp(path, "refs/", 5))
+		else if (!prefixcmp(path, "refs/"))
 			path = path + 5;
 
 		name_rev(commit, xstrdup(path), 0, 0, deref);
@@ -156,7 +156,7 @@ int cmd_name_rev(int argc, const char **argv, const char *prefix)
 			} else if (!strcmp(*argv, "--tags")) {
 				data.tags_only = 1;
 				continue;
-			} else  if (!strncmp(*argv, "--refs=", 7)) {
+			} else  if (!prefixcmp(*argv, "--refs=")) {
 				data.ref_filter = *argv + 7;
 				continue;
 			} else if (!strcmp(*argv, "--all")) {
diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 3824ee33a..71113d8fb 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -1579,14 +1579,14 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 			incremental = 1;
 			continue;
 		}
-		if (!strncmp("--window=", arg, 9)) {
+		if (!(-prefixcmp(arg, "--window="))) {
 			char *end;
 			window = strtoul(arg+9, &end, 0);
 			if (!arg[9] || *end)
 				usage(pack_usage);
 			continue;
 		}
-		if (!strncmp("--depth=", arg, 8)) {
+		if (!(-prefixcmp(arg, "--depth="))) {
 			char *end;
 			depth = strtoul(arg+8, &end, 0);
 			if (!arg[8] || *end)
@@ -1622,7 +1622,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 		if (!strcmp("--unpacked", arg) ||
-		    !strncmp("--unpacked=", arg, 11) ||
+		    !(-prefixcmp(arg, "--unpacked=")) ||
 		    !strcmp("--reflog", arg) ||
 		    !strcmp("--all", arg)) {
 			use_internal_rev_list = 1;
diff --git a/builtin-pack-refs.c b/builtin-pack-refs.c
index 3de9b3eef..d080e30d6 100644
--- a/builtin-pack-refs.c
+++ b/builtin-pack-refs.c
@@ -36,7 +36,7 @@ static int handle_one_ref(const char *path, const unsigned char *sha1,
 	/* Do not pack the symbolic refs */
 	if ((flags & REF_ISSYMREF))
 		return 0;
-	is_tag_ref = !strncmp(path, "refs/tags/", 10);
+	is_tag_ref = !prefixcmp(path, "refs/tags/");
 
 	/* ALWAYS pack refs that were already packed or are tags */
 	if (!cb->all && !is_tag_ref && !(flags & REF_ISPACKED))
diff --git a/builtin-push.c b/builtin-push.c
index c45649e26..2b98ba323 100644
--- a/builtin-push.c
+++ b/builtin-push.c
@@ -32,7 +32,7 @@ static int expand_one_ref(const char *ref, const unsigned char *sha1, int flag,
 	/* Ignore the "refs/" at the beginning of the refname */
 	ref += 5;
 
-	if (!strncmp(ref, "tags/", 5))
+	if (!prefixcmp(ref, "tags/"))
 		add_refspec(xstrdup(ref));
 	return 0;
 }
@@ -149,10 +149,10 @@ static int get_remotes_uri(const char *repo, const char *uri[MAX_URI])
 		int is_refspec;
 		char *s, *p;
 
-		if (!strncmp("URL:", buffer, 4)) {
+		if (!(-prefixcmp(buffer, "URL:"))) {
 			is_refspec = 0;
 			s = buffer + 4;
-		} else if (!strncmp("Push:", buffer, 5)) {
+		} else if (!(-prefixcmp(buffer, "Push:"))) {
 			is_refspec = 1;
 			s = buffer + 5;
 		} else
@@ -195,7 +195,7 @@ static int config_get_receivepack;
 
 static int get_remote_config(const char* key, const char* value)
 {
-	if (!strncmp(key, "remote.", 7) &&
+	if (!prefixcmp(key, "remote.") &&
 	    !strncmp(key + 7, config_repo, config_repo_len)) {
 		if (!strcmp(key + 7 + config_repo_len, ".url")) {
 			if (config_current_uri < MAX_URI)
@@ -324,8 +324,8 @@ static int do_push(const char *repo)
 		const char **dest_refspec = refspec;
 		const char *dest = uri[i];
 		const char *sender = "git-send-pack";
-		if (!strncmp(dest, "http://", 7) ||
-		    !strncmp(dest, "https://", 8))
+		if (!prefixcmp(dest, "http://") ||
+		    !prefixcmp(dest, "https://"))
 			sender = "git-http-push";
 		else if (thin)
 			argv[dest_argc++] = "--thin";
@@ -373,7 +373,7 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 			verbose=1;
 			continue;
 		}
-		if (!strncmp(arg, "--repo=", 7)) {
+		if (!prefixcmp(arg, "--repo=")) {
 			repo = arg+7;
 			continue;
 		}
@@ -397,11 +397,11 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 			thin = 0;
 			continue;
 		}
-		if (!strncmp(arg, "--receive-pack=", 15)) {
+		if (!prefixcmp(arg, "--receive-pack=")) {
 			receivepack = arg;
 			continue;
 		}
-		if (!strncmp(arg, "--exec=", 7)) {
+		if (!prefixcmp(arg, "--exec=")) {
 			receivepack = arg;
 			continue;
 		}
diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 8ba436dba..e47715538 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -133,7 +133,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		 *  entries and put the entries from the tree under the
 		 * given subdirectory.
 		 */
-		if (!strncmp(arg, "--prefix=", 9)) {
+		if (!prefixcmp(arg, "--prefix=")) {
 			if (stage || opts.merge || opts.prefix)
 				usage(read_tree_usage);
 			opts.prefix = arg + 9;
@@ -179,7 +179,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 			continue;
 		}
 
-		if (!strncmp(arg, "--exclude-per-directory=", 24)) {
+		if (!prefixcmp(arg, "--exclude-per-directory=")) {
 			struct dir_struct *dir;
 
 			if (opts.dir)
diff --git a/builtin-reflog.c b/builtin-reflog.c
index 341555139..cefb40da8 100644
--- a/builtin-reflog.c
+++ b/builtin-reflog.c
@@ -321,9 +321,9 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 		const char *arg = argv[i];
 		if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
 			cb.dry_run = 1;
-		else if (!strncmp(arg, "--expire=", 9))
+		else if (!prefixcmp(arg, "--expire="))
 			cb.expire_total = approxidate(arg + 9);
-		else if (!strncmp(arg, "--expire-unreachable=", 21))
+		else if (!prefixcmp(arg, "--expire-unreachable="))
 			cb.expire_unreachable = approxidate(arg + 21);
 		else if (!strcmp(arg, "--stale-fix"))
 			cb.stalefix = 1;
diff --git a/builtin-rerere.c b/builtin-rerere.c
index 318d959d8..978105b49 100644
--- a/builtin-rerere.c
+++ b/builtin-rerere.c
@@ -105,11 +105,11 @@ static int handle_file(const char *path,
 		SHA1_Init(&ctx);
 
 	while (fgets(buf, sizeof(buf), f)) {
-		if (!strncmp("<<<<<<< ", buf, 8))
+		if (!(-prefixcmp(buf, "<<<<<<< ")))
 			hunk = 1;
-		else if (!strncmp("=======", buf, 7))
+		else if (!(-prefixcmp(buf, "=======")))
 			hunk = 2;
-		else if (!strncmp(">>>>>>> ", buf, 8)) {
+		else if (!(-prefixcmp(buf, ">>>>>>> "))) {
 			hunk_no++;
 			hunk = 0;
 			if (memcmp(one->ptr, two->ptr, one->nr < two->nr ?
diff --git a/builtin-rev-parse.c b/builtin-rev-parse.c
index d53deaa36..a1c341112 100644
--- a/builtin-rev-parse.c
+++ b/builtin-rev-parse.c
@@ -274,7 +274,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 				continue;
 			}
 			if (!strcmp(arg, "--short") ||
-			    !strncmp(arg, "--short=", 8)) {
+			    !prefixcmp(arg, "--short=")) {
 				filter &= ~(DO_FLAGS|DO_NOREV);
 				verify = 1;
 				abbrev = DEFAULT_ABBREV;
@@ -352,19 +352,19 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 						: "false");
 				continue;
 			}
-			if (!strncmp(arg, "--since=", 8)) {
+			if (!prefixcmp(arg, "--since=")) {
 				show_datestring("--max-age=", arg+8);
 				continue;
 			}
-			if (!strncmp(arg, "--after=", 8)) {
+			if (!prefixcmp(arg, "--after=")) {
 				show_datestring("--max-age=", arg+8);
 				continue;
 			}
-			if (!strncmp(arg, "--before=", 9)) {
+			if (!prefixcmp(arg, "--before=")) {
 				show_datestring("--min-age=", arg+9);
 				continue;
 			}
-			if (!strncmp(arg, "--until=", 8)) {
+			if (!prefixcmp(arg, "--until=")) {
 				show_datestring("--min-age=", arg+8);
 				continue;
 			}
diff --git a/builtin-shortlog.c b/builtin-shortlog.c
index edb40429e..2f71a2a6e 100644
--- a/builtin-shortlog.c
+++ b/builtin-shortlog.c
@@ -124,7 +124,7 @@ static void insert_author_oneline(struct path_list *list,
 	else
 		free(buffer);
 
-	if (!strncmp(oneline, "[PATCH", 6)) {
+	if (!prefixcmp(oneline, "[PATCH")) {
 		char *eob = strchr(oneline, ']');
 
 		if (eob) {
@@ -179,7 +179,7 @@ static void read_from_stdin(struct path_list *list)
 	while (fgets(buffer, sizeof(buffer), stdin) != NULL) {
 		char *bob;
 		if ((buffer[0] == 'A' || buffer[0] == 'a') &&
-				!strncmp(buffer + 1, "uthor: ", 7) &&
+				!prefixcmp(buffer + 1, "uthor: ") &&
 				(bob = strchr(buffer + 7, '<')) != NULL) {
 			char buffer2[1024], offset = 0;
 
@@ -230,7 +230,7 @@ static void get_from_rev(struct rev_info *rev, struct path_list *list)
 			else
 				eol++;
 
-			if (!strncmp(buffer, "author ", 7)) {
+			if (!prefixcmp(buffer, "author ")) {
 				char *bracket = strchr(buffer, '<');
 
 				if (bracket == NULL || bracket > eol)
diff --git a/builtin-show-branch.c b/builtin-show-branch.c
index 0d94e40df..bf6aee49f 100644
--- a/builtin-show-branch.c
+++ b/builtin-show-branch.c
@@ -266,7 +266,7 @@ static void show_one_commit(struct commit *commit, int no_name)
 				    pretty, sizeof(pretty), 0, NULL, NULL, 0);
 	else
 		strcpy(pretty, "(unavailable)");
-	if (!strncmp(pretty, "[PATCH] ", 8))
+	if (!prefixcmp(pretty, "[PATCH] "))
 		cp = pretty + 8;
 	else
 		cp = pretty;
@@ -404,7 +404,7 @@ static int append_remote_ref(const char *refname, const unsigned char *sha1, int
 
 static int append_tag_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
 {
-	if (strncmp(refname, "refs/tags/", 10))
+	if (prefixcmp(refname, "refs/tags/"))
 		return 0;
 	return append_ref(refname + 5, sha1, 0);
 }
@@ -435,9 +435,9 @@ static int append_matching_ref(const char *refname, const unsigned char *sha1, i
 		return 0;
 	if (fnmatch(match_ref_pattern, tail, 0))
 		return 0;
-	if (!strncmp("refs/heads/", refname, 11))
+	if (!(-prefixcmp(refname, "refs/heads/")))
 		return append_head_ref(refname, sha1, flag, cb_data);
-	if (!strncmp("refs/tags/", refname, 10))
+	if (!(-prefixcmp(refname, "refs/tags/")))
 		return append_tag_ref(refname, sha1, flag, cb_data);
 	return append_ref(refname, sha1, 0);
 }
@@ -462,11 +462,11 @@ static int rev_is_head(char *head, int headlen, char *name,
 	if ((!head[0]) ||
 	    (head_sha1 && sha1 && hashcmp(head_sha1, sha1)))
 		return 0;
-	if (!strncmp(head, "refs/heads/", 11))
+	if (!prefixcmp(head, "refs/heads/"))
 		head += 11;
-	if (!strncmp(name, "refs/heads/", 11))
+	if (!prefixcmp(name, "refs/heads/"))
 		name += 11;
-	else if (!strncmp(name, "heads/", 6))
+	else if (!prefixcmp(name, "heads/"))
 		name += 6;
 	return !strcmp(head, name);
 }
@@ -635,7 +635,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			with_current_branch = 1;
 		else if (!strcmp(arg, "--sha1-name"))
 			sha1_name = 1;
-		else if (!strncmp(arg, "--more=", 7))
+		else if (!prefixcmp(arg, "--more="))
 			extra = atoi(arg + 7);
 		else if (!strcmp(arg, "--merge-base"))
 			merge_base = 1;
@@ -652,9 +652,9 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 		else if (!strcmp(arg, "--reflog") || !strcmp(arg, "-g")) {
 			reflog = DEFAULT_REFLOG;
 		}
-		else if (!strncmp(arg, "--reflog=", 9))
+		else if (!prefixcmp(arg, "--reflog="))
 			parse_reflog_param(arg + 9, &reflog, &reflog_base);
-		else if (!strncmp(arg, "-g=", 3))
+		else if (!prefixcmp(arg, "-g="))
 			parse_reflog_param(arg + 3, &reflog, &reflog_base);
 		else
 			usage(show_branch_usage);
diff --git a/builtin-show-ref.c b/builtin-show-ref.c
index 853f13f6a..ae0edddac 100644
--- a/builtin-show-ref.c
+++ b/builtin-show-ref.c
@@ -28,8 +28,8 @@ static int show_ref(const char *refname, const unsigned char *sha1, int flag, vo
 	if (tags_only || heads_only) {
 		int match;
 
-		match = heads_only && !strncmp(refname, "refs/heads/", 11);
-		match |= tags_only && !strncmp(refname, "refs/tags/", 10);
+		match = heads_only && !prefixcmp(refname, "refs/heads/");
+		match |= tags_only && !prefixcmp(refname, "refs/tags/");
 		if (!match)
 			return 0;
 	}
@@ -178,8 +178,8 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
 			hash_only = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--hash=", 7) ||
-		    (!strncmp(arg, "--abbrev", 8) &&
+		if (!prefixcmp(arg, "--hash=") ||
+		    (!prefixcmp(arg, "--abbrev") &&
 		     (arg[8] == '=' || arg[8] == '\0'))) {
 			if (arg[2] != 'h' && !arg[8])
 				/* --abbrev only */
@@ -215,7 +215,7 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
 		}
 		if (!strcmp(arg, "--exclude-existing"))
 			return exclude_existing(NULL);
-		if (!strncmp(arg, "--exclude-existing=", 19))
+		if (!prefixcmp(arg, "--exclude-existing="))
 			return exclude_existing(arg + 19);
 		usage(show_ref_usage);
 	}
@@ -224,7 +224,7 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
 		unsigned char sha1[20];
 
 		while (*pattern) {
-			if (!strncmp(*pattern, "refs/", 5) &&
+			if (!prefixcmp(*pattern, "refs/") &&
 			    resolve_ref(*pattern, sha1, 1, NULL)) {
 				if (!quiet)
 					show_one(*pattern, sha1);
diff --git a/builtin-tar-tree.c b/builtin-tar-tree.c
index 8055ddab9..28f8c1c16 100644
--- a/builtin-tar-tree.c
+++ b/builtin-tar-tree.c
@@ -31,7 +31,7 @@ int cmd_tar_tree(int argc, const char **argv, const char *prefix)
 	nargv[nargc++] = "git-archive";
 	nargv[nargc++] = "--format=tar";
 
-	if (2 <= argc && !strncmp("--remote=", argv[1], 9)) {
+	if (2 <= argc && !(-prefixcmp(argv[1], "--remote="))) {
 		nargv[nargc++] = argv[1];
 		argv++;
 		argc--;
diff --git a/builtin-unpack-objects.c b/builtin-unpack-objects.c
index d351e0264..8f8e89851 100644
--- a/builtin-unpack-objects.c
+++ b/builtin-unpack-objects.c
@@ -369,7 +369,7 @@ int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 				recover = 1;
 				continue;
 			}
-			if (!strncmp(arg, "--pack_header=", 14)) {
+			if (!prefixcmp(arg, "--pack_header=")) {
 				struct pack_header *hdr;
 				char *c;
 
diff --git a/builtin-write-tree.c b/builtin-write-tree.c
index 50670dc7b..90fc1cfcf 100644
--- a/builtin-write-tree.c
+++ b/builtin-write-tree.c
@@ -70,7 +70,7 @@ int cmd_write_tree(int argc, const char **argv, const char *unused_prefix)
 		const char *arg = argv[1];
 		if (!strcmp(arg, "--missing-ok"))
 			missing_ok = 1;
-		else if (!strncmp(arg, "--prefix=", 9))
+		else if (!prefixcmp(arg, "--prefix="))
 			prefix = arg + 9;
 		else
 			usage(write_tree_usage);
diff --git a/connect.c b/connect.c
index 78448889d..8a8a13bb7 100644
--- a/connect.c
+++ b/connect.c
@@ -96,7 +96,7 @@ int get_ack(int fd, unsigned char *result_sha1)
 		line[--len] = 0;
 	if (!strcmp(line, "NAK"))
 		return 0;
-	if (!strncmp(line, "ACK ", 4)) {
+	if (!prefixcmp(line, "ACK ")) {
 		if (!get_sha1_hex(line+4, result_sha1)) {
 			if (strstr(line+45, "continue"))
 				return 2;
@@ -196,8 +196,8 @@ static int count_refspec_match(const char *pattern,
 		 */
 		if (namelen != patlen &&
 		    patlen != namelen - 5 &&
-		    strncmp(name, "refs/heads/", 11) &&
-		    strncmp(name, "refs/tags/", 10)) {
+		    prefixcmp(name, "refs/heads/") &&
+		    prefixcmp(name, "refs/tags/")) {
 			/* We want to catch the case where only weak
 			 * matches are found and there are multiple
 			 * matches, and where more than one strong
diff --git a/daemon.c b/daemon.c
index 66f8d6f03..cdbc23f63 100644
--- a/daemon.c
+++ b/daemon.c
@@ -286,7 +286,7 @@ static int service_enabled;
 
 static int git_daemon_config(const char *var, const char *value)
 {
-	if (!strncmp(var, "daemon.", 7) &&
+	if (!prefixcmp(var, "daemon.") &&
 	    !strcmp(var + 7, service_looking_at->config_name)) {
 		service_enabled = git_config_bool(var, value);
 		return 0;
@@ -562,7 +562,7 @@ static int execute(struct sockaddr *addr)
 	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 		struct daemon_service *s = &(daemon_service[i]);
 		int namelen = strlen(s->name);
-		if (!strncmp("git-", line, 4) &&
+		if (!(-prefixcmp(line, "git-")) &&
 		    !strncmp(s->name, line + 4, namelen) &&
 		    line[namelen + 4] == ' ') {
 			/*
@@ -1011,7 +1011,7 @@ int main(int argc, char **argv)
 	for (i = 1; i < argc; i++) {
 		char *arg = argv[i];
 
-		if (!strncmp(arg, "--listen=", 9)) {
+		if (!prefixcmp(arg, "--listen=")) {
 		    char *p = arg + 9;
 		    char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
 		    while (*p)
@@ -1019,7 +1019,7 @@ int main(int argc, char **argv)
 		    *ph = 0;
 		    continue;
 		}
-		if (!strncmp(arg, "--port=", 7)) {
+		if (!prefixcmp(arg, "--port=")) {
 			char *end;
 			unsigned long n;
 			n = strtoul(arg+7, &end, 0);
@@ -1045,11 +1045,11 @@ int main(int argc, char **argv)
 			export_all_trees = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--timeout=", 10)) {
+		if (!prefixcmp(arg, "--timeout=")) {
 			timeout = atoi(arg+10);
 			continue;
 		}
-		if (!strncmp(arg, "--init-timeout=", 15)) {
+		if (!prefixcmp(arg, "--init-timeout=")) {
 			init_timeout = atoi(arg+15);
 			continue;
 		}
@@ -1057,11 +1057,11 @@ int main(int argc, char **argv)
 			strict_paths = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--base-path=", 12)) {
+		if (!prefixcmp(arg, "--base-path=")) {
 			base_path = arg+12;
 			continue;
 		}
-		if (!strncmp(arg, "--interpolated-path=", 20)) {
+		if (!prefixcmp(arg, "--interpolated-path=")) {
 			interpolated_path = arg+20;
 			continue;
 		}
@@ -1073,11 +1073,11 @@ int main(int argc, char **argv)
 			user_path = "";
 			continue;
 		}
-		if (!strncmp(arg, "--user-path=", 12)) {
+		if (!prefixcmp(arg, "--user-path=")) {
 			user_path = arg + 12;
 			continue;
 		}
-		if (!strncmp(arg, "--pid-file=", 11)) {
+		if (!prefixcmp(arg, "--pid-file=")) {
 			pid_file = arg + 11;
 			continue;
 		}
@@ -1086,27 +1086,27 @@ int main(int argc, char **argv)
 			log_syslog = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--user=", 7)) {
+		if (!prefixcmp(arg, "--user=")) {
 			user_name = arg + 7;
 			continue;
 		}
-		if (!strncmp(arg, "--group=", 8)) {
+		if (!prefixcmp(arg, "--group=")) {
 			group_name = arg + 8;
 			continue;
 		}
-		if (!strncmp(arg, "--enable=", 9)) {
+		if (!prefixcmp(arg, "--enable=")) {
 			enable_service(arg + 9, 1);
 			continue;
 		}
-		if (!strncmp(arg, "--disable=", 10)) {
+		if (!prefixcmp(arg, "--disable=")) {
 			enable_service(arg + 10, 0);
 			continue;
 		}
-		if (!strncmp(arg, "--allow-override=", 17)) {
+		if (!prefixcmp(arg, "--allow-override=")) {
 			make_service_overridable(arg + 17, 1);
 			continue;
 		}
-		if (!strncmp(arg, "--forbid-override=", 18)) {
+		if (!prefixcmp(arg, "--forbid-override=")) {
 			make_service_overridable(arg + 18, 0);
 			continue;
 		}
diff --git a/diff.c b/diff.c
index 07589c3b1..fad13ab44 100644
--- a/diff.c
+++ b/diff.c
@@ -77,7 +77,7 @@ int git_diff_ui_config(const char *var, const char *value)
 			diff_detect_rename_default = DIFF_DETECT_RENAME;
 		return 0;
 	}
-	if (!strncmp(var, "diff.color.", 11) || !strncmp(var, "color.diff.", 11)) {
+	if (!prefixcmp(var, "diff.color.") || !strncmp(var, "color.diff.", 11)) {
 		int slot = parse_diff_color_slot(var, 11);
 		color_parse(value, var, diff_colors[slot]);
 		return 0;
@@ -1119,9 +1119,9 @@ static void builtin_diff(const char *name_a,
 		xecfg.flags = XDL_EMIT_FUNCNAMES;
 		if (!diffopts)
 			;
-		else if (!strncmp(diffopts, "--unified=", 10))
+		else if (!prefixcmp(diffopts, "--unified="))
 			xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
-		else if (!strncmp(diffopts, "-u", 2))
+		else if (!prefixcmp(diffopts, "-u"))
 			xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
 		ecb.outf = xdiff_outf;
 		ecb.priv = &ecbdata;
@@ -1957,7 +1957,7 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	else if (!strcmp(arg, "--shortstat")) {
 		options->output_format |= DIFF_FORMAT_SHORTSTAT;
 	}
-	else if (!strncmp(arg, "--stat", 6)) {
+	else if (!prefixcmp(arg, "--stat")) {
 		char *end;
 		int width = options->stat_width;
 		int name_width = options->stat_name_width;
@@ -1966,9 +1966,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 
 		switch (*arg) {
 		case '-':
-			if (!strncmp(arg, "-width=", 7))
+			if (!prefixcmp(arg, "-width="))
 				width = strtoul(arg + 7, &end, 10);
-			else if (!strncmp(arg, "-name-width=", 12))
+			else if (!prefixcmp(arg, "-name-width="))
 				name_width = strtoul(arg + 12, &end, 10);
 			break;
 		case '=':
@@ -1993,7 +1993,7 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	}
 	else if (!strcmp(arg, "-z"))
 		options->line_termination = 0;
-	else if (!strncmp(arg, "-l", 2))
+	else if (!prefixcmp(arg, "-l"))
 		options->rename_limit = strtoul(arg+2, NULL, 10);
 	else if (!strcmp(arg, "--full-index"))
 		options->full_index = 1;
@@ -2010,31 +2010,31 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->output_format |= DIFF_FORMAT_NAME_STATUS;
 	else if (!strcmp(arg, "-R"))
 		options->reverse_diff = 1;
-	else if (!strncmp(arg, "-S", 2))
+	else if (!prefixcmp(arg, "-S"))
 		options->pickaxe = arg + 2;
 	else if (!strcmp(arg, "-s")) {
 		options->output_format |= DIFF_FORMAT_NO_OUTPUT;
 	}
-	else if (!strncmp(arg, "-O", 2))
+	else if (!prefixcmp(arg, "-O"))
 		options->orderfile = arg + 2;
-	else if (!strncmp(arg, "--diff-filter=", 14))
+	else if (!prefixcmp(arg, "--diff-filter="))
 		options->filter = arg + 14;
 	else if (!strcmp(arg, "--pickaxe-all"))
 		options->pickaxe_opts = DIFF_PICKAXE_ALL;
 	else if (!strcmp(arg, "--pickaxe-regex"))
 		options->pickaxe_opts = DIFF_PICKAXE_REGEX;
-	else if (!strncmp(arg, "-B", 2)) {
+	else if (!prefixcmp(arg, "-B")) {
 		if ((options->break_opt =
 		     diff_scoreopt_parse(arg)) == -1)
 			return -1;
 	}
-	else if (!strncmp(arg, "-M", 2)) {
+	else if (!prefixcmp(arg, "-M")) {
 		if ((options->rename_score =
 		     diff_scoreopt_parse(arg)) == -1)
 			return -1;
 		options->detect_rename = DIFF_DETECT_RENAME;
 	}
-	else if (!strncmp(arg, "-C", 2)) {
+	else if (!prefixcmp(arg, "-C")) {
 		if ((options->rename_score =
 		     diff_scoreopt_parse(arg)) == -1)
 			return -1;
@@ -2044,7 +2044,7 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->find_copies_harder = 1;
 	else if (!strcmp(arg, "--abbrev"))
 		options->abbrev = DEFAULT_ABBREV;
-	else if (!strncmp(arg, "--abbrev=", 9)) {
+	else if (!prefixcmp(arg, "--abbrev=")) {
 		options->abbrev = strtoul(arg + 9, NULL, 10);
 		if (options->abbrev < MINIMUM_ABBREV)
 			options->abbrev = MINIMUM_ABBREV;
@@ -2553,7 +2553,7 @@ static void patch_id_consume(void *priv, char *line, unsigned long len)
 	int new_len;
 
 	/* Ignore line numbers when computing the SHA1 of the patch */
-	if (!strncmp(line, "@@ -", 4))
+	if (!prefixcmp(line, "@@ -"))
 		return;
 
 	new_len = remove_space(line, len);
diff --git a/exec_cmd.c b/exec_cmd.c
index 3996bce33..9b74ed2f4 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -56,7 +56,7 @@ int execv_git_cmd(const char **argv)
 			len = strlen(git_command);
 
 			/* Trivial cleanup */
-			while (!strncmp(exec_dir, "./", 2)) {
+			while (!prefixcmp(exec_dir, "./")) {
 				exec_dir += 2;
 				while (*exec_dir == '/')
 					exec_dir++;
diff --git a/fast-import.c b/fast-import.c
index 32cd1f83e..8e192c299 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1392,7 +1392,7 @@ static void read_next_command(void)
 
 static void cmd_mark(void)
 {
-	if (!strncmp("mark :", command_buf.buf, 6)) {
+	if (!(-prefixcmp(command_buf.buf, "mark :"))) {
 		next_mark = strtoumax(command_buf.buf + 6, NULL, 10);
 		read_next_command();
 	}
@@ -1405,10 +1405,10 @@ static void *cmd_data (size_t *size)
 	size_t length;
 	char *buffer;
 
-	if (strncmp("data ", command_buf.buf, 5))
+	if ((-prefixcmp(command_buf.buf, "data ")))
 		die("Expected 'data n' command, found: %s", command_buf.buf);
 
-	if (!strncmp("<<", command_buf.buf + 5, 2)) {
+	if (!(-prefixcmp(command_buf.buf + 5, "<<"))) {
 		char *term = xstrdup(command_buf.buf + 5 + 2);
 		size_t sz = 8192, term_len = command_buf.len - 5 - 2;
 		length = 0;
@@ -1595,7 +1595,7 @@ static void file_change_m(struct branch *b)
 		oe = find_mark(strtoumax(p + 1, &x, 10));
 		hashcpy(sha1, oe->sha1);
 		p = x;
-	} else if (!strncmp("inline", p, 6)) {
+	} else if (!(-prefixcmp(p, "inline"))) {
 		inline_data = 1;
 		p += 6;
 	} else {
@@ -1668,7 +1668,7 @@ static void cmd_from(struct branch *b)
 	const char *from;
 	struct branch *s;
 
-	if (strncmp("from ", command_buf.buf, 5))
+	if ((-prefixcmp(command_buf.buf, "from ")))
 		return;
 
 	if (b->branch_tree.tree) {
@@ -1734,7 +1734,7 @@ static struct hash_list *cmd_merge(unsigned int *count)
 	struct branch *s;
 
 	*count = 0;
-	while (!strncmp("merge ", command_buf.buf, 6)) {
+	while (!(-prefixcmp(command_buf.buf, "merge "))) {
 		from = strchr(command_buf.buf, ' ') + 1;
 		n = xmalloc(sizeof(*n));
 		s = lookup_branch(from);
@@ -1780,11 +1780,11 @@ static void cmd_new_commit(void)
 
 	read_next_command();
 	cmd_mark();
-	if (!strncmp("author ", command_buf.buf, 7)) {
+	if (!(-prefixcmp(command_buf.buf, "author "))) {
 		author = parse_ident(command_buf.buf + 7);
 		read_next_command();
 	}
-	if (!strncmp("committer ", command_buf.buf, 10)) {
+	if (!(-prefixcmp(command_buf.buf, "committer "))) {
 		committer = parse_ident(command_buf.buf + 10);
 		read_next_command();
 	}
@@ -1805,9 +1805,9 @@ static void cmd_new_commit(void)
 	for (;;) {
 		if (1 == command_buf.len)
 			break;
-		else if (!strncmp("M ", command_buf.buf, 2))
+		else if (!(-prefixcmp(command_buf.buf, "M ")))
 			file_change_m(b);
-		else if (!strncmp("D ", command_buf.buf, 2))
+		else if (!(-prefixcmp(command_buf.buf, "D ")))
 			file_change_d(b);
 		else if (!strcmp("deleteall", command_buf.buf))
 			file_change_deleteall(b);
@@ -1877,7 +1877,7 @@ static void cmd_new_tag(void)
 	read_next_command();
 
 	/* from ... */
-	if (strncmp("from ", command_buf.buf, 5))
+	if ((-prefixcmp(command_buf.buf, "from ")))
 		die("Expected from command, got %s", command_buf.buf);
 	from = strchr(command_buf.buf, ' ') + 1;
 	s = lookup_branch(from);
@@ -1904,7 +1904,7 @@ static void cmd_new_tag(void)
 	read_next_command();
 
 	/* tagger ... */
-	if (strncmp("tagger ", command_buf.buf, 7))
+	if ((-prefixcmp(command_buf.buf, "tagger ")))
 		die("Expected tagger command, got %s", command_buf.buf);
 	tagger = parse_ident(command_buf.buf + 7);
 
@@ -1981,7 +1981,7 @@ int main(int argc, const char **argv)
 
 		if (*a != '-' || !strcmp(a, "--"))
 			break;
-		else if (!strncmp(a, "--date-format=", 14)) {
+		else if (!prefixcmp(a, "--date-format=")) {
 			const char *fmt = a + 14;
 			if (!strcmp(fmt, "raw"))
 				whenspec = WHENSPEC_RAW;
@@ -1992,15 +1992,15 @@ int main(int argc, const char **argv)
 			else
 				die("unknown --date-format argument %s", fmt);
 		}
-		else if (!strncmp(a, "--max-pack-size=", 16))
+		else if (!prefixcmp(a, "--max-pack-size="))
 			max_packsize = strtoumax(a + 16, NULL, 0) * 1024 * 1024;
-		else if (!strncmp(a, "--depth=", 8))
+		else if (!prefixcmp(a, "--depth="))
 			max_depth = strtoul(a + 8, NULL, 0);
-		else if (!strncmp(a, "--active-branches=", 18))
+		else if (!prefixcmp(a, "--active-branches="))
 			max_active_branches = strtoul(a + 18, NULL, 0);
-		else if (!strncmp(a, "--export-marks=", 15))
+		else if (!prefixcmp(a, "--export-marks="))
 			mark_file = a + 15;
-		else if (!strncmp(a, "--export-pack-edges=", 20)) {
+		else if (!prefixcmp(a, "--export-pack-edges=")) {
 			if (pack_edges)
 				fclose(pack_edges);
 			pack_edges = fopen(a + 20, "a");
@@ -2033,11 +2033,11 @@ int main(int argc, const char **argv)
 			break;
 		else if (!strcmp("blob", command_buf.buf))
 			cmd_new_blob();
-		else if (!strncmp("commit ", command_buf.buf, 7))
+		else if (!(-prefixcmp(command_buf.buf, "commit ")))
 			cmd_new_commit();
-		else if (!strncmp("tag ", command_buf.buf, 4))
+		else if (!(-prefixcmp(command_buf.buf, "tag ")))
 			cmd_new_tag();
-		else if (!strncmp("reset ", command_buf.buf, 6))
+		else if (!(-prefixcmp(command_buf.buf, "reset ")))
 			cmd_reset_branch();
 		else if (!strcmp("checkpoint", command_buf.buf))
 			cmd_checkpoint();
diff --git a/fetch-pack.c b/fetch-pack.c
index c78710676..1fd2c3adf 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -198,13 +198,13 @@ static int find_common(int fd[2], unsigned char *result_sha1,
 		int len;
 
 		while ((len = packet_read_line(fd[0], line, sizeof(line)))) {
-			if (!strncmp("shallow ", line, 8)) {
+			if (!(-prefixcmp(line, "shallow "))) {
 				if (get_sha1_hex(line + 8, sha1))
 					die("invalid shallow line: %s", line);
 				register_shallow(sha1);
 				continue;
 			}
-			if (!strncmp("unshallow ", line, 10)) {
+			if (!(-prefixcmp(line, "unshallow "))) {
 				if (get_sha1_hex(line + 10, sha1))
 					die("invalid unshallow line: %s", line);
 				if (!lookup_object(sha1))
@@ -346,7 +346,7 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
 		    check_ref_format(ref->name + 5))
 			; /* trash */
 		else if (fetch_all &&
-			 (!depth || strncmp(ref->name, "refs/tags/", 10) )) {
+			 (!depth || prefixcmp(ref->name, "refs/tags/") )) {
 			*newtail = ref;
 			ref->next = NULL;
 			newtail = &ref->next;
@@ -683,11 +683,11 @@ int main(int argc, char **argv)
 		char *arg = argv[i];
 
 		if (*arg == '-') {
-			if (!strncmp("--upload-pack=", arg, 14)) {
+			if (!(-prefixcmp(arg, "--upload-pack="))) {
 				uploadpack = arg + 14;
 				continue;
 			}
-			if (!strncmp("--exec=", arg, 7)) {
+			if (!(-prefixcmp(arg, "--exec="))) {
 				uploadpack = arg + 7;
 				continue;
 			}
@@ -712,7 +712,7 @@ int main(int argc, char **argv)
 				verbose = 1;
 				continue;
 			}
-			if (!strncmp("--depth=", arg, 8)) {
+			if (!(-prefixcmp(arg, "--depth="))) {
 				depth = strtol(arg + 8, NULL, 0);
 				if (stat(git_path("shallow"), &st))
 					st.st_mtime = 0;
diff --git a/git.c b/git.c
index 4dd196721..1fad85206 100644
--- a/git.c
+++ b/git.c
@@ -48,7 +48,7 @@ static int handle_options(const char*** argv, int* argc)
 		/*
 		 * Check remaining flags.
 		 */
-		if (!strncmp(cmd, "--exec-path", 11)) {
+		if (!prefixcmp(cmd, "--exec-path")) {
 			cmd += 11;
 			if (*cmd == '=')
 				git_set_exec_path(cmd + 1);
@@ -66,7 +66,7 @@ static int handle_options(const char*** argv, int* argc)
 			setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 			(*argv)++;
 			(*argc)--;
-		} else if (!strncmp(cmd, "--git-dir=", 10)) {
+		} else if (!prefixcmp(cmd, "--git-dir=")) {
 			setenv(GIT_DIR_ENVIRONMENT, cmd + 10, 1);
 		} else if (!strcmp(cmd, "--bare")) {
 			static char git_dir[PATH_MAX+1];
@@ -88,7 +88,7 @@ static char *alias_string;
 
 static int git_alias_config(const char *var, const char *value)
 {
-	if (!strncmp(var, "alias.", 6) && !strcmp(var + 6, alias_command)) {
+	if (!prefixcmp(var, "alias.") && !strcmp(var + 6, alias_command)) {
 		alias_string = xstrdup(value);
 	}
 	return 0;
@@ -348,7 +348,7 @@ int main(int argc, const char **argv, char **envp)
 	 * So we just directly call the internal command handler, and
 	 * die if that one cannot handle it.
 	 */
-	if (!strncmp(cmd, "git-", 4)) {
+	if (!prefixcmp(cmd, "git-")) {
 		cmd += 4;
 		argv[0] = cmd;
 		handle_internal_command(argc, argv, envp);
@@ -360,7 +360,7 @@ int main(int argc, const char **argv, char **envp)
 	argc--;
 	handle_options(&argv, &argc);
 	if (argc > 0) {
-		if (!strncmp(argv[0], "--", 2))
+		if (!prefixcmp(argv[0], "--"))
 			argv[0] += 2;
 	} else {
 		/* Default command: "help" */
diff --git a/help.c b/help.c
index b6674635a..0893fea02 100644
--- a/help.c
+++ b/help.c
@@ -130,7 +130,7 @@ static void list_commands(const char *exec_path, const char *pattern)
 		struct stat st;
 		int entlen;
 
-		if (strncmp(de->d_name, "git-", 4))
+		if (prefixcmp(de->d_name, "git-"))
 			continue;
 		strcpy(path+dirlen, de->d_name);
 		if (stat(path, &st) || /* stat, not lstat */
@@ -179,7 +179,7 @@ static void show_man_page(const char *git_cmd)
 {
 	const char *page;
 
-	if (!strncmp(git_cmd, "git", 3))
+	if (!prefixcmp(git_cmd, "git"))
 		page = git_cmd;
 	else {
 		int page_len = strlen(git_cmd) + 4;
diff --git a/http-fetch.c b/http-fetch.c
index 9f790a08e..d9a4561c8 100644
--- a/http-fetch.c
+++ b/http-fetch.c
@@ -717,7 +717,7 @@ static int fetch_indices(struct alt_base *repo)
 		case 'P':
 			i++;
 			if (i + 52 <= buffer.posn &&
-			    !strncmp(data + i, " pack-", 6) &&
+			    !prefixcmp(data + i, " pack-") &&
 			    !strncmp(data + i + 46, ".pack\n", 6)) {
 				get_sha1_hex(data + i + 6, sha1);
 				setup_index(repo, sha1);
diff --git a/http-push.c b/http-push.c
index b128c0146..eb77c9af4 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1060,7 +1060,7 @@ static int fetch_indices(void)
 		case 'P':
 			i++;
 			if (i + 52 < buffer.posn &&
-			    !strncmp(data + i, " pack-", 6) &&
+			    !prefixcmp(data + i, " pack-") &&
 			    !strncmp(data + i + 46, ".pack\n", 6)) {
 				get_sha1_hex(data + i + 6, sha1);
 				setup_index(sha1);
@@ -1206,11 +1206,11 @@ static void handle_new_lock_ctx(struct xml_ctx *ctx, int tag_closed)
 			lock->owner = xmalloc(strlen(ctx->cdata) + 1);
 			strcpy(lock->owner, ctx->cdata);
 		} else if (!strcmp(ctx->name, DAV_ACTIVELOCK_TIMEOUT)) {
-			if (!strncmp(ctx->cdata, "Second-", 7))
+			if (!prefixcmp(ctx->cdata, "Second-"))
 				lock->timeout =
 					strtol(ctx->cdata + 7, NULL, 10);
 		} else if (!strcmp(ctx->name, DAV_ACTIVELOCK_TOKEN)) {
-			if (!strncmp(ctx->cdata, "opaquelocktoken:", 16)) {
+			if (!prefixcmp(ctx->cdata, "opaquelocktoken:")) {
 				lock->token = xmalloc(strlen(ctx->cdata) - 15);
 				strcpy(lock->token, ctx->cdata + 16);
 			}
@@ -2168,7 +2168,7 @@ static void fetch_symref(const char *path, char **symref, unsigned char *sha1)
 		return;
 
 	/* If it's a symref, set the refname; otherwise try for a sha1 */
-	if (!strncmp((char *)buffer.buffer, "ref: ", 5)) {
+	if (!prefixcmp((char *)buffer.buffer, "ref: ")) {
 		*symref = xmalloc(buffer.posn - 5);
 		strlcpy(*symref, (char *)buffer.buffer + 5, buffer.posn - 5);
 	} else {
diff --git a/index-pack.c b/index-pack.c
index 72e096241..fa9a0e748 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -849,9 +849,9 @@ int main(int argc, char **argv)
 				fix_thin_pack = 1;
 			} else if (!strcmp(arg, "--keep")) {
 				keep_msg = "";
-			} else if (!strncmp(arg, "--keep=", 7)) {
+			} else if (!prefixcmp(arg, "--keep=")) {
 				keep_msg = arg + 7;
-			} else if (!strncmp(arg, "--pack_header=", 14)) {
+			} else if (!prefixcmp(arg, "--pack_header=")) {
 				struct pack_header *hdr;
 				char *c;
 
diff --git a/peek-remote.c b/peek-remote.c
index ef3c76ce5..7b66228a2 100644
--- a/peek-remote.c
+++ b/peek-remote.c
@@ -35,11 +35,11 @@ int main(int argc, char **argv)
 		char *arg = argv[i];
 
 		if (*arg == '-') {
-			if (!strncmp("--upload-pack=", arg, 14)) {
+			if (!(-prefixcmp(arg, "--upload-pack="))) {
 				uploadpack = arg + 14;
 				continue;
 			}
-			if (!strncmp("--exec=", arg, 7)) {
+			if (!(-prefixcmp(arg, "--exec="))) {
 				uploadpack = arg + 7;
 				continue;
 			}
diff --git a/receive-pack.c b/receive-pack.c
index 7311c822d..7f1dcc045 100644
--- a/receive-pack.c
+++ b/receive-pack.c
@@ -109,7 +109,7 @@ static int update(struct command *cmd)
 	struct ref_lock *lock;
 
 	cmd->error_string = NULL;
-	if (!strncmp(name, "refs/", 5) && check_ref_format(name + 5)) {
+	if (!prefixcmp(name, "refs/") && check_ref_format(name + 5)) {
 		cmd->error_string = "funny refname";
 		return error("refusing to create funny ref '%s' locally",
 			     name);
@@ -125,7 +125,7 @@ static int update(struct command *cmd)
 	}
 	if (deny_non_fast_forwards && !is_null_sha1(new_sha1) &&
 	    !is_null_sha1(old_sha1) &&
-	    !strncmp(name, "refs/heads/", 11)) {
+	    !prefixcmp(name, "refs/heads/")) {
 		struct commit *old_commit, *new_commit;
 		struct commit_list *bases, *ent;
 
diff --git a/refs.c b/refs.c
index 638770378..d347876c8 100644
--- a/refs.c
+++ b/refs.c
@@ -828,8 +828,8 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 		goto rollback;
 	}
 
-	if (!strncmp(oldref, "refs/heads/", 11) &&
-			!strncmp(newref, "refs/heads/", 11)) {
+	if (!prefixcmp(oldref, "refs/heads/") &&
+			!prefixcmp(newref, "refs/heads/")) {
 		char oldsection[1024], newsection[1024];
 
 		snprintf(oldsection, 1024, "branch.%s", oldref + 11);
@@ -894,8 +894,8 @@ static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
 	log_file = git_path("logs/%s", ref_name);
 
 	if (log_all_ref_updates &&
-	    (!strncmp(ref_name, "refs/heads/", 11) ||
-	     !strncmp(ref_name, "refs/remotes/", 13) ||
+	    (!prefixcmp(ref_name, "refs/heads/") ||
+	     !prefixcmp(ref_name, "refs/remotes/") ||
 	     !strcmp(ref_name, "HEAD"))) {
 		if (safe_create_leading_directories(log_file) < 0)
 			return error("unable to create directory for %s",
diff --git a/revision.c b/revision.c
index 5b1794b0e..abab3b9d0 100644
--- a/revision.c
+++ b/revision.c
@@ -813,11 +813,11 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 		const char *arg = argv[i];
 		if (*arg == '-') {
 			int opts;
-			if (!strncmp(arg, "--max-count=", 12)) {
+			if (!prefixcmp(arg, "--max-count=")) {
 				revs->max_count = atoi(arg + 12);
 				continue;
 			}
-			if (!strncmp(arg, "--skip=", 7)) {
+			if (!prefixcmp(arg, "--skip=")) {
 				revs->skip_count = atoi(arg + 7);
 				continue;
 			}
@@ -836,27 +836,27 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				revs->max_count = atoi(arg + 2);
 				continue;
 			}
-			if (!strncmp(arg, "--max-age=", 10)) {
+			if (!prefixcmp(arg, "--max-age=")) {
 				revs->max_age = atoi(arg + 10);
 				continue;
 			}
-			if (!strncmp(arg, "--since=", 8)) {
+			if (!prefixcmp(arg, "--since=")) {
 				revs->max_age = approxidate(arg + 8);
 				continue;
 			}
-			if (!strncmp(arg, "--after=", 8)) {
+			if (!prefixcmp(arg, "--after=")) {
 				revs->max_age = approxidate(arg + 8);
 				continue;
 			}
-			if (!strncmp(arg, "--min-age=", 10)) {
+			if (!prefixcmp(arg, "--min-age=")) {
 				revs->min_age = atoi(arg + 10);
 				continue;
 			}
-			if (!strncmp(arg, "--before=", 9)) {
+			if (!prefixcmp(arg, "--before=")) {
 				revs->min_age = approxidate(arg + 9);
 				continue;
 			}
-			if (!strncmp(arg, "--until=", 8)) {
+			if (!prefixcmp(arg, "--until=")) {
 				revs->min_age = approxidate(arg + 8);
 				continue;
 			}
@@ -944,7 +944,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				revs->num_ignore_packed = 0;
 				continue;
 			}
-			if (!strncmp(arg, "--unpacked=", 11)) {
+			if (!prefixcmp(arg, "--unpacked=")) {
 				revs->unpacked = 1;
 				add_ignore_packed(revs, arg+11);
 				continue;
@@ -980,7 +980,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				revs->verbose_header = 1;
 				continue;
 			}
-			if (!strncmp(arg, "--pretty", 8)) {
+			if (!prefixcmp(arg, "--pretty")) {
 				revs->verbose_header = 1;
 				revs->commit_format = get_commit_format(arg+8);
 				continue;
@@ -1005,7 +1005,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				revs->abbrev = DEFAULT_ABBREV;
 				continue;
 			}
-			if (!strncmp(arg, "--abbrev=", 9)) {
+			if (!prefixcmp(arg, "--abbrev=")) {
 				revs->abbrev = strtoul(arg + 9, NULL, 10);
 				if (revs->abbrev < MINIMUM_ABBREV)
 					revs->abbrev = MINIMUM_ABBREV;
@@ -1034,15 +1034,15 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 			/*
 			 * Grepping the commit log
 			 */
-			if (!strncmp(arg, "--author=", 9)) {
+			if (!prefixcmp(arg, "--author=")) {
 				add_header_grep(revs, "author", arg+9);
 				continue;
 			}
-			if (!strncmp(arg, "--committer=", 12)) {
+			if (!prefixcmp(arg, "--committer=")) {
 				add_header_grep(revs, "committer", arg+12);
 				continue;
 			}
-			if (!strncmp(arg, "--grep=", 7)) {
+			if (!prefixcmp(arg, "--grep=")) {
 				add_message_grep(revs, arg+7);
 				continue;
 			}
@@ -1050,7 +1050,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				all_match = 1;
 				continue;
 			}
-			if (!strncmp(arg, "--encoding=", 11)) {
+			if (!prefixcmp(arg, "--encoding=")) {
 				arg += 11;
 				if (strcmp(arg, "none"))
 					git_log_output_encoding = strdup(arg);
diff --git a/send-pack.c b/send-pack.c
index 33e69dbe1..512b660e9 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -379,11 +379,11 @@ int main(int argc, char **argv)
 		char *arg = *argv;
 
 		if (*arg == '-') {
-			if (!strncmp(arg, "--receive-pack=", 15)) {
+			if (!prefixcmp(arg, "--receive-pack=")) {
 				receivepack = arg + 15;
 				continue;
 			}
-			if (!strncmp(arg, "--exec=", 7)) {
+			if (!prefixcmp(arg, "--exec=")) {
 				receivepack = arg + 7;
 				continue;
 			}
diff --git a/setup.c b/setup.c
index e9d3f5aab..dda67d268 100644
--- a/setup.c
+++ b/setup.c
@@ -251,7 +251,7 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	offset++;
 	cwd[len++] = '/';
 	cwd[len] = 0;
-	inside_git_dir = !strncmp(cwd + offset, ".git/", 5);
+	inside_git_dir = !prefixcmp(cwd + offset, ".git/");
 	return cwd + offset;
 }
 
diff --git a/shell.c b/shell.c
index 8c08cf0fb..c983fc7b8 100644
--- a/shell.c
+++ b/shell.c
@@ -8,7 +8,7 @@ static int do_generic_cmd(const char *me, char *arg)
 
 	if (!arg || !(arg = sq_dequote(arg)))
 		die("bad argument");
-	if (strncmp(me, "git-", 4))
+	if (prefixcmp(me, "git-"))
 		die("bad command");
 
 	my_argv[0] = me + 4;
diff --git a/upload-pack.c b/upload-pack.c
index 3648aae1a..d7876cade 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -455,7 +455,7 @@ static int get_common_commits(void)
 			continue;
 		}
 		len = strip(line, len);
-		if (!strncmp(line, "have ", 5)) {
+		if (!prefixcmp(line, "have ")) {
 			switch (got_sha1(line+5, sha1)) {
 			case -1: /* they have what we do not */
 				if (multi_ack && ok_to_give_up())
@@ -502,7 +502,7 @@ static void receive_needs(void)
 		if (!len)
 			break;
 
-		if (!strncmp("shallow ", line, 8)) {
+		if (!(-prefixcmp(line, "shallow "))) {
 			unsigned char sha1[20];
 			struct object *object;
 			use_thin_pack = 0;
@@ -515,7 +515,7 @@ static void receive_needs(void)
 			add_object_array(object, NULL, &shallows);
 			continue;
 		}
-		if (!strncmp("deepen ", line, 7)) {
+		if (!(-prefixcmp(line, "deepen "))) {
 			char *end;
 			use_thin_pack = 0;
 			depth = strtol(line + 7, &end, 0);
@@ -523,7 +523,7 @@ static void receive_needs(void)
 				die("Invalid deepen: %s", line);
 			continue;
 		}
-		if (strncmp("want ", line, 5) ||
+		if ((-prefixcmp(line, "want ")) ||
 		    get_sha1_hex(line+5, sha1_buf))
 			die("git-upload-pack: protocol error, "
 			    "expected to get sha, not '%s'", line);
@@ -656,7 +656,7 @@ int main(int argc, char **argv)
 			strict = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--timeout=", 10)) {
+		if (!prefixcmp(arg, "--timeout=")) {
 			timeout = atoi(arg+10);
 			continue;
 		}
diff --git a/wt-status.c b/wt-status.c
index 2879c3d5e..d17a6ba5b 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -298,7 +298,7 @@ void wt_status_print(struct wt_status *s)
 	if (s->branch) {
 		const char *on_what = "On branch ";
 		const char *branch_name = s->branch;
-		if (!strncmp(branch_name, "refs/heads/", 11))
+		if (!prefixcmp(branch_name, "refs/heads/"))
 			branch_name += 11;
 		else if (!strcmp(branch_name, "HEAD")) {
 			branch_name = "";
@@ -344,7 +344,7 @@ int git_status_config(const char *k, const char *v)
 		wt_status_use_color = git_config_colorbool(k, v);
 		return 0;
 	}
-	if (!strncmp(k, "status.color.", 13) || !strncmp(k, "color.status.", 13)) {
+	if (!prefixcmp(k, "status.color.") || !strncmp(k, "color.status.", 13)) {
 		int slot = parse_status_slot(k, 13);
 		color_parse(v, k, wt_status_colors[slot]);
 	}