Merge branch 'jk/argv-array'

* jk/argv-array:
  run_hook: use argv_array API
  checkout: use argv_array API
  bisect: use argv_array API
  quote: provide sq_dequote_to_argv_array
  refactor argv_array into generic code
  quote.h: fix bogus comment
  add sha1_array API docs

11 files changed, 261 insertions, 107 deletions

diff --git a/Documentation/technical/api-argv-array.txt b/Documentation/technical/api-argv-array.txt
new file mode 100644
index 000000000..49b3d5295
--- /dev/null
+++ b/Documentation/technical/api-argv-array.txt
@@ -0,0 +1,46 @@
+argv-array API
+==============
+
+The argv-array API allows one to dynamically build and store
+NULL-terminated lists.  An argv-array maintains the invariant that the
+`argv` member always points to a non-NULL array, and that the array is
+always NULL-terminated at the element pointed to by `argv[argc]`. This
+makes the result suitable for passing to functions expecting to receive
+argv from main(), or the link:api-run-command.html[run-command API].
+
+The link:api-string-list.html[string-list API] is similar, but cannot be
+used for these purposes; instead of storing a straight string pointer,
+it contains an item structure with a `util` field that is not compatible
+with the traditional argv interface.
+
+Each `argv_array` manages its own memory. Any strings pushed into the
+array are duplicated, and all memory is freed by argv_array_clear().
+
+Data Structures
+---------------
+
+`struct argv_array`::
+
+	A single array. This should be initialized by assignment from
+	`ARGV_ARRAY_INIT`, or by calling `argv_array_init`. The `argv`
+	member contains the actual array; the `argc` member contains the
+	number of elements in the array, not including the terminating
+	NULL.
+
+Functions
+---------
+
+`argv_array_init`::
+	Initialize an array. This is no different than assigning from
+	`ARGV_ARRAY_INIT`.
+
+`argv_array_push`::
+	Push a copy of a string onto the end of the array.
+
+`argv_array_pushf`::
+	Format a string and push it onto the end of the array. This is a
+	convenience wrapper combining `strbuf_addf` and `argv_array_push`.
+
+`argv_array_clear`::
+	Free all memory associated with the array and return it to the
+	initial, empty state.
diff --git a/Documentation/technical/api-sha1-array.txt b/Documentation/technical/api-sha1-array.txt
new file mode 100644
index 000000000..4a4bae810
--- /dev/null
+++ b/Documentation/technical/api-sha1-array.txt
@@ -0,0 +1,79 @@
+sha1-array API
+==============
+
+The sha1-array API provides storage and manipulation of sets of SHA1
+identifiers. The emphasis is on storage and processing efficiency,
+making them suitable for large lists. Note that the ordering of items is
+not preserved over some operations.
+
+Data Structures
+---------------
+
+`struct sha1_array`::
+
+	A single array of SHA1 hashes. This should be initialized by
+	assignment from `SHA1_ARRAY_INIT`.  The `sha1` member contains
+	the actual data. The `nr` member contains the number of items in
+	the set.  The `alloc` and `sorted` members are used internally,
+	and should not be needed by API callers.
+
+Functions
+---------
+
+`sha1_array_append`::
+	Add an item to the set. The sha1 will be placed at the end of
+	the array (but note that some operations below may lose this
+	ordering).
+
+`sha1_array_sort`::
+	Sort the elements in the array.
+
+`sha1_array_lookup`::
+	Perform a binary search of the array for a specific sha1.
+	If found, returns the offset (in number of elements) of the
+	sha1. If not found, returns a negative integer. If the array is
+	not sorted, this function has the side effect of sorting it.
+
+`sha1_array_clear`::
+	Free all memory associated with the array and return it to the
+	initial, empty state.
+
+`sha1_array_for_each_unique`::
+	Efficiently iterate over each unique element of the list,
+	executing the callback function for each one. If the array is
+	not sorted, this function has the side effect of sorting it.
+
+Examples
+--------
+
+-----------------------------------------
+void print_callback(const unsigned char sha1[20],
+		    void *data)
+{
+	printf("%s\n", sha1_to_hex(sha1));
+}
+
+void some_func(void)
+{
+	struct sha1_array hashes = SHA1_ARRAY_INIT;
+	unsigned char sha1[20];
+
+	/* Read objects into our set */
+	while (read_object_from_stdin(sha1))
+		sha1_array_append(&hashes, sha1);
+
+	/* Check if some objects are in our set */
+	while (read_object_from_stdin(sha1)) {
+		if (sha1_array_lookup(&hashes, sha1) >= 0)
+			printf("it's in there!\n");
+
+	/*
+	 * Print the unique set of objects. We could also have
+	 * avoided adding duplicate objects in the first place,
+	 * but we would end up re-sorting the array repeatedly.
+	 * Instead, this will sort once and then skip duplicates
+	 * in linear time.
+	 */
+	sha1_array_for_each_unique(&hashes, print_callback, NULL);
+}
+-----------------------------------------
diff --git a/Makefile b/Makefile
index 4a8191c8d..cd5888b9a 100644
--- a/Makefile
+++ b/Makefile
@@ -501,6 +501,7 @@ VCSSVN_LIB=vcs-svn/lib.a
 
 LIB_H += advice.h
 LIB_H += archive.h
+LIB_H += argv-array.h
 LIB_H += attr.h
 LIB_H += blob.h
 LIB_H += builtin.h
@@ -584,6 +585,7 @@ LIB_OBJS += alloc.o
 LIB_OBJS += archive.o
 LIB_OBJS += archive-tar.o
 LIB_OBJS += archive-zip.o
+LIB_OBJS += argv-array.o
 LIB_OBJS += attr.o
 LIB_OBJS += base85.o
 LIB_OBJS += bisect.o
diff --git a/argv-array.c b/argv-array.c
new file mode 100644
index 000000000..a4e04201e
--- /dev/null
+++ b/argv-array.c
@@ -0,0 +1,51 @@
+#include "cache.h"
+#include "argv-array.h"
+#include "strbuf.h"
+
+static const char *empty_argv_storage = NULL;
+const char **empty_argv = &empty_argv_storage;
+
+void argv_array_init(struct argv_array *array)
+{
+	array->argv = empty_argv;
+	array->argc = 0;
+	array->alloc = 0;
+}
+
+static void argv_array_push_nodup(struct argv_array *array, const char *value)
+{
+	if (array->argv == empty_argv)
+		array->argv = NULL;
+
+	ALLOC_GROW(array->argv, array->argc + 2, array->alloc);
+	array->argv[array->argc++] = value;
+	array->argv[array->argc] = NULL;
+}
+
+void argv_array_push(struct argv_array *array, const char *value)
+{
+	argv_array_push_nodup(array, xstrdup(value));
+}
+
+void argv_array_pushf(struct argv_array *array, const char *fmt, ...)
+{
+	va_list ap;
+	struct strbuf v = STRBUF_INIT;
+
+	va_start(ap, fmt);
+	strbuf_vaddf(&v, fmt, ap);
+	va_end(ap);
+
+	argv_array_push_nodup(array, strbuf_detach(&v, NULL));
+}
+
+void argv_array_clear(struct argv_array *array)
+{
+	if (array->argv != empty_argv) {
+		int i;
+		for (i = 0; i < array->argc; i++)
+			free((char **)array->argv[i]);
+		free(array->argv);
+	}
+	argv_array_init(array);
+}
diff --git a/argv-array.h b/argv-array.h
new file mode 100644
index 000000000..74dd2b1bc
--- /dev/null
+++ b/argv-array.h
@@ -0,0 +1,20 @@
+#ifndef ARGV_ARRAY_H
+#define ARGV_ARRAY_H
+
+extern const char **empty_argv;
+
+struct argv_array {
+	const char **argv;
+	int argc;
+	int alloc;
+};
+
+#define ARGV_ARRAY_INIT { empty_argv, 0, 0 }
+
+void argv_array_init(struct argv_array *);
+void argv_array_push(struct argv_array *, const char *);
+__attribute__((format (printf,2,3)))
+void argv_array_pushf(struct argv_array *, const char *fmt, ...);
+void argv_array_clear(struct argv_array *);
+
+#endif /* ARGV_ARRAY_H */
diff --git a/bisect.c b/bisect.c
index c7b7d7913..de05bf824 100644
--- a/bisect.c
+++ b/bisect.c
@@ -10,18 +10,13 @@
 #include "log-tree.h"
 #include "bisect.h"
 #include "sha1-array.h"
+#include "argv-array.h"
 
 static struct sha1_array good_revs;
 static struct sha1_array skipped_revs;
 
 static const unsigned char *current_bad_sha1;
 
-struct argv_array {
-	const char **argv;
-	int argv_nr;
-	int argv_alloc;
-};
-
 static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
 static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
 static const char *argv_update_ref[] = {"update-ref", "--no-deref", "BISECT_HEAD", NULL, NULL};
@@ -405,21 +400,6 @@ struct commit_list *find_bisection(struct commit_list *list,
 	return best;
 }
 
-static void argv_array_push(struct argv_array *array, const char *string)
-{
-	ALLOC_GROW(array->argv, array->argv_nr + 1, array->argv_alloc);
-	array->argv[array->argv_nr++] = string;
-}
-
-static void argv_array_push_sha1(struct argv_array *array,
-				 const unsigned char *sha1,
-				 const char *format)
-{
-	struct strbuf buf = STRBUF_INIT;
-	strbuf_addf(&buf, format, sha1_to_hex(sha1));
-	argv_array_push(array, strbuf_detach(&buf, NULL));
-}
-
 static int register_ref(const char *refname, const unsigned char *sha1,
 			int flags, void *cb_data)
 {
@@ -449,16 +429,10 @@ static void read_bisect_paths(struct argv_array *array)
 		die_errno("Could not open file '%s'", filename);
 
 	while (strbuf_getline(&str, fp, '\n') != EOF) {
-		char *quoted;
-		int res;
-
 		strbuf_trim(&str);
-		quoted = strbuf_detach(&str, NULL);
-		res = sq_dequote_to_argv(quoted, &array->argv,
-					 &array->argv_nr, &array->argv_alloc);
-		if (res)
+		if (sq_dequote_to_argv_array(str.buf, array))
 			die("Badly quoted content in file '%s': %s",
-			    filename, quoted);
+			    filename, str.buf);
 	}
 
 	strbuf_release(&str);
@@ -623,7 +597,7 @@ static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
 			     const char *bad_format, const char *good_format,
 			     int read_paths)
 {
-	struct argv_array rev_argv = { NULL, 0, 0 };
+	struct argv_array rev_argv = ARGV_ARRAY_INIT;
 	int i;
 
 	init_revisions(revs, prefix);
@@ -631,17 +605,17 @@ static void bisect_rev_setup(struct rev_info *revs, const char *prefix,
 	revs->commit_format = CMIT_FMT_UNSPECIFIED;
 
 	/* rev_argv.argv[0] will be ignored by setup_revisions */
-	argv_array_push(&rev_argv, xstrdup("bisect_rev_setup"));
-	argv_array_push_sha1(&rev_argv, current_bad_sha1, bad_format);
+	argv_array_push(&rev_argv, "bisect_rev_setup");
+	argv_array_pushf(&rev_argv, bad_format, sha1_to_hex(current_bad_sha1));
 	for (i = 0; i < good_revs.nr; i++)
-		argv_array_push_sha1(&rev_argv, good_revs.sha1[i],
-				     good_format);
-	argv_array_push(&rev_argv, xstrdup("--"));
+		argv_array_pushf(&rev_argv, good_format,
+				 sha1_to_hex(good_revs.sha1[i]));
+	argv_array_push(&rev_argv, "--");
 	if (read_paths)
 		read_bisect_paths(&rev_argv);
-	argv_array_push(&rev_argv, NULL);
 
-	setup_revisions(rev_argv.argv_nr, rev_argv.argv, revs, NULL);
+	setup_revisions(rev_argv.argc, rev_argv.argv, revs, NULL);
+	/* XXX leak rev_argv, as "revs" may still be pointing to it */
 }
 
 static void bisect_common(struct rev_info *revs)
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 5e356a6c6..8210ccc13 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -19,6 +19,7 @@
 #include "ll-merge.h"
 #include "resolve-undo.h"
 #include "submodule.h"
+#include "argv-array.h"
 
 static const char * const checkout_usage[] = {
 	"git checkout [options] <branch>",
@@ -588,24 +589,12 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 		report_tracking(new);
 }
 
-struct rev_list_args {
-	int argc;
-	int alloc;
-	const char **argv;
-};
-
-static void add_one_rev_list_arg(struct rev_list_args *args, const char *s)
-{
-	ALLOC_GROW(args->argv, args->argc + 1, args->alloc);
-	args->argv[args->argc++] = s;
-}
-
 static int add_one_ref_to_rev_list_arg(const char *refname,
 				       const unsigned char *sha1,
 				       int flags,
 				       void *cb_data)
 {
-	add_one_rev_list_arg(cb_data, refname);
+	argv_array_push(cb_data, refname);
 	return 0;
 }
 
@@ -685,15 +674,14 @@ static void suggest_reattach(struct commit *commit, struct rev_info *revs)
  */
 static void orphaned_commit_warning(struct commit *commit)
 {
-	struct rev_list_args args = { 0, 0, NULL };
+	struct argv_array args = ARGV_ARRAY_INIT;
 	struct rev_info revs;
 
-	add_one_rev_list_arg(&args, "(internal)");
-	add_one_rev_list_arg(&args, sha1_to_hex(commit->object.sha1));
-	add_one_rev_list_arg(&args, "--not");
+	argv_array_push(&args, "(internal)");
+	argv_array_push(&args, sha1_to_hex(commit->object.sha1));
+	argv_array_push(&args, "--not");
 	for_each_ref(add_one_ref_to_rev_list_arg, &args);
-	add_one_rev_list_arg(&args, "--");
-	add_one_rev_list_arg(&args, NULL);
+	argv_array_push(&args, "--");
 
 	init_revisions(&revs, NULL);
 	if (setup_revisions(args.argc - 1, args.argv, &revs, NULL) != 1)
@@ -705,6 +693,7 @@ static void orphaned_commit_warning(struct commit *commit)
 	else
 		describe_detached_head(_("Previous HEAD position was"), commit);
 
+	argv_array_clear(&args);
 	clear_commit_marks(commit, -1);
 	for_each_ref(clear_commit_marks_from_one_ref, NULL);
 }
diff --git a/quote.c b/quote.c
index 532fd3b7b..911229fdf 100644
--- a/quote.c
+++ b/quote.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "quote.h"
+#include "argv-array.h"
 
 int quote_path_fully = 1;
 
@@ -120,7 +121,9 @@ char *sq_dequote(char *arg)
 	return sq_dequote_step(arg, NULL);
 }
 
-int sq_dequote_to_argv(char *arg, const char ***argv, int *nr, int *alloc)
+static int sq_dequote_to_argv_internal(char *arg,
+				       const char ***argv, int *nr, int *alloc,
+				       struct argv_array *array)
 {
 	char *next = arg;
 
@@ -130,13 +133,27 @@ int sq_dequote_to_argv(char *arg, const char ***argv, int *nr, int *alloc)
 		char *dequoted = sq_dequote_step(next, &next);
 		if (!dequoted)
 			return -1;
-		ALLOC_GROW(*argv, *nr + 1, *alloc);
-		(*argv)[(*nr)++] = dequoted;
+		if (argv) {
+			ALLOC_GROW(*argv, *nr + 1, *alloc);
+			(*argv)[(*nr)++] = dequoted;
+		}
+		if (array)
+			argv_array_push(array, dequoted);
 	} while (next);
 
 	return 0;
 }
 
+int sq_dequote_to_argv(char *arg, const char ***argv, int *nr, int *alloc)
+{
+	return sq_dequote_to_argv_internal(arg, argv, nr, alloc, NULL);
+}
+
+int sq_dequote_to_argv_array(char *arg, struct argv_array *array)
+{
+	return sq_dequote_to_argv_internal(arg, NULL, NULL, NULL, array);
+}
+
 /* 1 means: quote as octal
  * 0 means: quote as octal if (quote_path_fully)
  * -1 means: never quote
diff --git a/quote.h b/quote.h
index 024e21d80..133155a48 100644
--- a/quote.h
+++ b/quote.h
@@ -40,12 +40,19 @@ extern char *sq_dequote(char *);
 
 /*
  * Same as the above, but can be used to unwrap many arguments in the
- * same string separated by space. "next" is changed to point to the
- * next argument that should be passed as first parameter. When there
- * is no more argument to be dequoted, "next" is updated to point to NULL.
+ * same string separated by space. Like sq_quote, it works in place,
+ * modifying arg and appending pointers into it to argv.
  */
 extern int sq_dequote_to_argv(char *arg, const char ***argv, int *nr, int *alloc);
 
+/*
+ * Same as above, but store the unquoted strings in an argv_array. We will
+ * still modify arg in place, but unlike sq_dequote_to_argv, the argv_array
+ * will duplicate and take ownership of the strings.
+ */
+struct argv_array;
+extern int sq_dequote_to_argv_array(char *arg, struct argv_array *);
+
 extern int unquote_c_style(struct strbuf *, const char *quoted, const char **endp);
 extern size_t quote_c_style(const char *name, struct strbuf *, FILE *, int no_dq);
 extern void quote_two_c_style(struct strbuf *, const char *, const char *, int);
diff --git a/run-command.c b/run-command.c
index a2796c4ca..1c5104388 100644
--- a/run-command.c
+++ b/run-command.c
@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "run-command.h"
 #include "exec_cmd.h"
+#include "argv-array.h"
 
 static inline void close_pair(int fd[2])
 {
@@ -605,26 +606,23 @@ int finish_async(struct async *async)
 int run_hook(const char *index_file, const char *name, ...)
 {
 	struct child_process hook;
-	const char **argv = NULL, *env[2];
+	struct argv_array argv = ARGV_ARRAY_INIT;
+	const char *p, *env[2];
 	char index[PATH_MAX];
 	va_list args;
 	int ret;
-	size_t i = 0, alloc = 0;
 
 	if (access(git_path("hooks/%s", name), X_OK) < 0)
 		return 0;
 
 	va_start(args, name);
-	ALLOC_GROW(argv, i + 1, alloc);
-	argv[i++] = git_path("hooks/%s", name);
-	while (argv[i-1]) {
-		ALLOC_GROW(argv, i + 1, alloc);
-		argv[i++] = va_arg(args, const char *);
-	}
+	argv_array_push(&argv, git_path("hooks/%s", name));
+	while ((p = va_arg(args, const char *)))
+		argv_array_push(&argv, p);
 	va_end(args);
 
 	memset(&hook, 0, sizeof(hook));
-	hook.argv = argv;
+	hook.argv = argv.argv;
 	hook.no_stdin = 1;
 	hook.stdout_to_stderr = 1;
 	if (index_file) {
@@ -635,6 +633,6 @@ int run_hook(const char *index_file, const char *name, ...)
 	}
 
 	ret = run_command(&hook);
-	free(argv);
+	argv_array_clear(&argv);
 	return ret;
 }
diff --git a/submodule.c b/submodule.c
index 08756387e..0b709bc29 100644
--- a/submodule.c
+++ b/submodule.c
@@ -9,6 +9,7 @@
 #include "refs.h"
 #include "string-list.h"
 #include "sha1-array.h"
+#include "argv-array.h"
 
 static struct string_list config_name_for_path;
 static struct string_list config_fetch_recurse_submodules_for_name;
@@ -496,56 +497,26 @@ void check_for_new_submodule_commits(unsigned char new_sha1[20])
 	sha1_array_append(&ref_tips_after_fetch, new_sha1);
 }
 
-struct argv_array {
-	const char **argv;
-	unsigned int argc;
-	unsigned int alloc;
-};
-
-static void init_argv(struct argv_array *array)
-{
-	array->argv = NULL;
-	array->argc = 0;
-	array->alloc = 0;
-}
-
-static void push_argv(struct argv_array *array, const char *value)
-{
-	ALLOC_GROW(array->argv, array->argc + 2, array->alloc);
-	array->argv[array->argc++] = xstrdup(value);
-	array->argv[array->argc] = NULL;
-}
-
-static void clear_argv(struct argv_array *array)
-{
-	int i;
-	for (i = 0; i < array->argc; i++)
-		free((char **)array->argv[i]);
-	free(array->argv);
-	init_argv(array);
-}
-
 static void add_sha1_to_argv(const unsigned char sha1[20], void *data)
 {
-	push_argv(data, sha1_to_hex(sha1));
+	argv_array_push(data, sha1_to_hex(sha1));
 }
 
 static void calculate_changed_submodule_paths(void)
 {
 	struct rev_info rev;
 	struct commit *commit;
-	struct argv_array argv;
+	struct argv_array argv = ARGV_ARRAY_INIT;
 
 	/* No need to check if there are no submodules configured */
 	if (!config_name_for_path.nr)
 		return;
 
 	init_revisions(&rev, NULL);
-	init_argv(&argv);
-	push_argv(&argv, "--"); /* argv[0] program name */
+	argv_array_push(&argv, "--"); /* argv[0] program name */
 	sha1_array_for_each_unique(&ref_tips_after_fetch,
 				   add_sha1_to_argv, &argv);
-	push_argv(&argv, "--not");
+	argv_array_push(&argv, "--not");
 	sha1_array_for_each_unique(&ref_tips_before_fetch,
 				   add_sha1_to_argv, &argv);
 	setup_revisions(argv.argc, argv.argv, &rev, NULL);
@@ -573,7 +544,7 @@ static void calculate_changed_submodule_paths(void)
 		}
 	}
 
-	clear_argv(&argv);
+	argv_array_clear(&argv);
 	sha1_array_clear(&ref_tips_before_fetch);
 	sha1_array_clear(&ref_tips_after_fetch);
 	initialized_fetch_ref_tips = 0;