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Win32: don't copy the environment twice when spawning child processes

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When spawning child processes via start_command(), the environment and all
environment entries are copied twice. First by make_augmented_environ /
copy_environ to merge with child_process.env. Then a second time by
make_environment_block to create a sorted environment block string as
required by CreateProcess.

Move the merge logic to make_environment_block so that we only need to copy
the environment once. This changes semantics of the env parameter: it now
expects a delta (such as child_process.env) rather than a full environment.
This is not a problem as the parameter is only used by start_command()
(all other callers previously passed char **environ, and now pass NULL).

The merge logic no longer xstrdup()s the environment strings, so do_putenv
must not free them. Add a parameter to distinguish this from normal putenv.

Remove the now unused make_augmented_environ / free_environ API.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Stepan Kasal <kasal@ucw.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Karsten Blees 2014-07-17 17:38:01 +02:00 committed by Junio C Hamano
parent df0e998c31
commit 77734da241
3 changed files with 30 additions and 64 deletions
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76
compat/mingw.c
View file

@ -899,6 +899,8 @@ static char *path_lookup(const char *cmd, char **path, int exe_only)
return prog;
}
static char **do_putenv(char **env, const char *name, int free_old);
static int compareenv(const void *a, const void *b)
{
char *const *ea = a;
@ -907,21 +909,30 @@ static int compareenv(const void *a, const void *b)
}
/*
* Create environment block suitable for CreateProcess.
* Create environment block suitable for CreateProcess. Merges current
* process environment and the supplied environment changes.
*/
static wchar_t *make_environment_block(char **env)
static wchar_t *make_environment_block(char **deltaenv)
{
wchar_t *wenvblk = NULL;
int count = 0;
char **e, **tmpenv;
int size = 0, wenvsz = 0, wenvpos = 0;
for (e = env; *e; e++)
while (environ[count])
count++;
/* environment must be sorted */
/* copy the environment */
tmpenv = xmalloc(sizeof(*tmpenv) * (count + 1));
memcpy(tmpenv, env, sizeof(*tmpenv) * (count + 1));
memcpy(tmpenv, environ, sizeof(*tmpenv) * (count + 1));
/* merge supplied environment changes into the temporary environment */
for (e = deltaenv; e && *e; e++)
tmpenv = do_putenv(tmpenv, *e, 0);
/* environment must be sorted */
for (count = 0; tmpenv[count]; )
count++;
qsort(tmpenv, count, sizeof(*tmpenv), compareenv);
/* create environment block from temporary environment */
@ -944,7 +955,7 @@ struct pinfo_t {
static struct pinfo_t *pinfo = NULL;
CRITICAL_SECTION pinfo_cs;
static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **env,
static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaenv,
const char *dir,
int prepend_cmd, int fhin, int fhout, int fherr)
{
@ -1012,8 +1023,7 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **env,
xutftowcs(wargs, args.buf, 2 * args.len + 1);
strbuf_release(&args);
if (env)
wenvblk = make_environment_block(env);
wenvblk = make_environment_block(deltaenv);
memset(&pi, 0, sizeof(pi));
ret = CreateProcessW(wcmd, wargs, NULL, NULL, TRUE, flags,
@ -1051,10 +1061,10 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **env,
static pid_t mingw_spawnv(const char *cmd, const char **argv, int prepend_cmd)
{
return mingw_spawnve_fd(cmd, argv, environ, NULL, prepend_cmd, 0, 1, 2);
return mingw_spawnve_fd(cmd, argv, NULL, NULL, prepend_cmd, 0, 1, 2);
}
pid_t mingw_spawnvpe(const char *cmd, const char **argv, char **env,
pid_t mingw_spawnvpe(const char *cmd, const char **argv, char **deltaenv,
const char *dir,
int fhin, int fhout, int fherr)
{
@ -1078,14 +1088,14 @@ pid_t mingw_spawnvpe(const char *cmd, const char **argv, char **env,
pid = -1;
}
else {
pid = mingw_spawnve_fd(iprog, argv, env, dir, 1,
pid = mingw_spawnve_fd(iprog, argv, deltaenv, dir, 1,
fhin, fhout, fherr);
free(iprog);
}
argv[0] = argv0;
}
else
pid = mingw_spawnve_fd(prog, argv, env, dir, 0,
pid = mingw_spawnve_fd(prog, argv, deltaenv, dir, 0,
fhin, fhout, fherr);
free(prog);
}
@ -1182,27 +1192,6 @@ int mingw_kill(pid_t pid, int sig)
return -1;
}
static char **copy_environ(void)
{
char **env;
int i = 0;
while (environ[i])
i++;
env = xmalloc((i+1)*sizeof(*env));
for (i = 0; environ[i]; i++)
env[i] = xstrdup(environ[i]);
env[i] = NULL;
return env;
}
void free_environ(char **env)
{
int i;
for (i = 0; env[i]; i++)
free(env[i]);
free(env);
}
static int lookupenv(char **env, const char *name, size_t nmln)
{
int i;
@ -1218,7 +1207,7 @@ static int lookupenv(char **env, const char *name, size_t nmln)
/*
* If name contains '=', then sets the variable, otherwise it unsets it
*/
static char **do_putenv(char **env, const char *name)
static char **do_putenv(char **env, const char *name, int free_old)
{
char *eq = strchrnul(name, '=');
int i = lookupenv(env, name, eq-name);
@ -1233,7 +1222,8 @@ static char **do_putenv(char **env, const char *name)
}
}
else {
free(env[i]);
if (free_old)
free(env[i]);
if (*eq)
env[i] = (char*) name;
else
@ -1243,20 +1233,6 @@ static char **do_putenv(char **env, const char *name)
return env;
}
/*
* Copies global environ and adjusts variables as specified by vars.
*/
char **make_augmented_environ(const char *const *vars)
{
char **env = copy_environ();
while (*vars) {
const char *v = *vars++;
env = do_putenv(env, strchr(v, '=') ? xstrdup(v) : v);
}
return env;
}
#undef getenv
char *mingw_getenv(const char *name)
{
@ -1272,7 +1248,7 @@ char *mingw_getenv(const char *name)
int mingw_putenv(const char *namevalue)
{
environ = do_putenv(environ, namevalue);
environ = do_putenv(environ, namevalue, 1);
return 0;
}

8
compat/mingw.h
View file

@ -357,12 +357,8 @@ int mingw_offset_1st_component(const char *path);
void mingw_open_html(const char *path);
#define open_html mingw_open_html
/*
* helpers
*/
char **make_augmented_environ(const char *const *vars);
void free_environ(char **env);
void mingw_mark_as_git_dir(const char *dir);
#define mark_as_git_dir mingw_mark_as_git_dir
/**
* Converts UTF-8 encoded string to UTF-16LE.

10
run-command.c
View file

@ -454,7 +454,6 @@ int start_command(struct child_process *cmd)
{
int fhin = 0, fhout = 1, fherr = 2;
const char **sargv = cmd->argv;
char **env = environ;
if (cmd->no_stdin)
fhin = open("/dev/null", O_RDWR);
@ -479,24 +478,19 @@ int start_command(struct child_process *cmd)
else if (cmd->out > 1)
fhout = dup(cmd->out);
if (cmd->env)
env = make_augmented_environ(cmd->env);
if (cmd->git_cmd)
cmd->argv = prepare_git_cmd(cmd->argv);
else if (cmd->use_shell)
cmd->argv = prepare_shell_cmd(cmd->argv);
cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env, cmd->dir,
fhin, fhout, fherr);
cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, (char**) cmd->env,
cmd->dir, fhin, fhout, fherr);
failed_errno = errno;
if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
if (cmd->clean_on_exit && cmd->pid >= 0)
mark_child_for_cleanup(cmd->pid);
if (cmd->env)
free_environ(env);
if (cmd->git_cmd)
free(cmd->argv);