From c1189caeaf726e6c16c8bca7da8bf0b243da478d Mon Sep 17 00:00:00 2001 From: Jeff King Date: Tue, 13 Sep 2011 17:57:57 -0400 Subject: refactor argv_array into generic code The submodule code recently grew generic code to build a dynamic argv array. Many other parts of the code can reuse this, too, so let's make it generically available. There are two enhancements not found in the original code: 1. We now handle the NULL-termination invariant properly, even when no strings have been pushed (before, you could have an empty, NULL argv). This was not a problem for the submodule code, which always pushed at least one argument, but was not sufficiently safe for generic code. 2. There is a formatted variant of the "push" function. This is a convenience function which was not needed by the submodule code, but will make it easier to port other users to the new code. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano diff --git a/Documentation/technical/api-argv-array.txt b/Documentation/technical/api-argv-array.txt new file mode 100644 index 0000000..49b3d52 --- /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/Makefile b/Makefile index e40ac0c..ec7d06c 100644 --- a/Makefile +++ b/Makefile @@ -497,6 +497,7 @@ 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 @@ -575,6 +576,7 @@ 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 0000000..a4e0420 --- /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 0000000..74dd2b1 --- /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/submodule.c b/submodule.c index 9431c42..6306737 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; @@ -388,52 +389,22 @@ 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; 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); @@ -460,7 +431,7 @@ 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; -- cgit v0.10.2-6-g49f6