path: root/Documentation/technical/api-argv-array.txt
diff options
authorJeff King <>2011-09-13 21:57:57 (GMT)
committerJunio C Hamano <>2011-09-14 18:56:36 (GMT)
commitc1189caeaf726e6c16c8bca7da8bf0b243da478d (patch)
tree8d8feeeef2e8584c11875da8dde2d04f334cb56b /Documentation/technical/api-argv-array.txt
parent7878b07c0d86d05fa505f2464557c69addcc2c05 (diff)
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 <>
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+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
+ Initialize an array. This is no different than assigning from
+ Push a copy of a string onto the end of the array.
+ Format a string and push it onto the end of the array. This is a
+ convenience wrapper combining `strbuf_addf` and `argv_array_push`.
+ Free all memory associated with the array and return it to the
+ initial, empty state.