run-command API: remove "env" member, always use "env_array"

Remove the "env" member from "struct child_process" in favor of always
using the "env_array". As with the preceding removal of "argv" in
favor of "args" this gets rid of current and future oddities around
memory management at the API boundary (see the amended API docs).

For some of the conversions we can replace patterns like:

    child.env = env->v;

With:

    strvec_pushv(&child.env_array, env->v);

But for others we need to guard the strvec_pushv() with a NULL check,
since we're not passing in the "v" member of a "struct strvec",
e.g. in the case of tmp_objdir_env()'s return value.

Ideally we'd rename the "env_array" member to simply "env" as a
follow-up, since it and "args" are now inconsistent in not having an
"_array" suffix, and seemingly without any good reason, unless we look
at the history of how they came to be.

But as we've currently got 122 in-tree hits for a "git grep env_array"
let's leave that for now (and possibly forever). Doing that rename
would be too disruptive.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 7 insertions, 13 deletions

diff --git a/run-command.c b/run-command.c
index 99dc93e..ebade08 100644
--- a/run-command.c
+++ b/run-command.c
@@ -655,12 +655,7 @@ static void trace_run_command(const struct child_process *cp)
 		sq_quote_buf_pretty(&buf, cp->dir);
 		strbuf_addch(&buf, ';');
 	}
-	/*
-	 * The caller is responsible for initializing cp->env from
-	 * cp->env_array if needed. We only check one place.
-	 */
-	if (cp->env)
-		trace_add_env(&buf, cp->env);
+	trace_add_env(&buf, cp->env_array.v);
 	if (cp->git_cmd)
 		strbuf_addstr(&buf, " git");
 	sq_quote_argv_pretty(&buf, cp->args.v);
@@ -676,9 +671,6 @@ int start_command(struct child_process *cmd)
 	int failed_errno;
 	char *str;
 
-	if (!cmd->env)
-		cmd->env = cmd->env_array.v;
-
 	/*
 	 * In case of errors we must keep the promise to close FDs
 	 * that have been passed in via ->in and ->out.
@@ -768,7 +760,7 @@ fail_pipe:
 		set_cloexec(null_fd);
 	}
 
-	childenv = prep_childenv(cmd->env);
+	childenv = prep_childenv(cmd->env_array.v);
 	atfork_prepare(&as);
 
 	/*
@@ -931,7 +923,7 @@ end_of_spawn:
 	else if (cmd->use_shell)
 		cmd->args.v = prepare_shell_cmd(&nargv, sargv);
 
-	cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v, (char**) cmd->env,
+	cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v, (char**) cmd->env_array.v,
 			cmd->dir, fhin, fhout, fherr);
 	failed_errno = errno;
 	if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
@@ -1047,7 +1039,8 @@ int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
 	cmd.wait_after_clean = opt & RUN_WAIT_AFTER_CLEAN ? 1 : 0;
 	cmd.close_object_store = opt & RUN_CLOSE_OBJECT_STORE ? 1 : 0;
 	cmd.dir = dir;
-	cmd.env = env;
+	if (env)
+		strvec_pushv(&cmd.env_array, (const char **)env);
 	cmd.trace2_child_class = tr2_class;
 	return run_command(&cmd);
 }
@@ -1333,7 +1326,8 @@ int run_hook_ve(const char *const *env, const char *name, va_list args)
 	strvec_push(&hook.args, p);
 	while ((p = va_arg(args, const char *)))
 		strvec_push(&hook.args, p);
-	hook.env = env;
+	if (env)
+		strvec_pushv(&hook.env_array, (const char **)env);
 	hook.no_stdin = 1;
 	hook.stdout_to_stderr = 1;
 	hook.trace2_hook_name = name;