In order to avoid allocation between 'fork()' and 'exec()' prepare the environment to be used in the child process prior to forking.
Signed-off-by: Brandon Williams <bmw...@google.com> --- run-command.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 75 insertions(+), 9 deletions(-) diff --git a/run-command.c b/run-command.c index 029d41463..84c63b209 100644 --- a/run-command.c +++ b/run-command.c @@ -291,6 +291,75 @@ static int wait_or_whine(pid_t pid, const char *argv0, int in_signal) return code; } +static int env_isequal(const char *e1, const char *e2) +{ + for (;;) { + char c1 = *e1++; + char c2 = *e2++; + c1 = (c1 == '=') ? '\0' : tolower(c1); + c2 = (c2 == '=') ? '\0' : tolower(c2); + + if (c1 != c2) + return 0; + if (c1 == '\0') + return 1; + } +} + +static int searchenv(char **env, const char *name) +{ + int pos = 0; + + for (; env[pos]; pos++) + if (env_isequal(env[pos], name)) + break; + + return pos; +} + +static int do_putenv(char **env, int env_nr, const char *name) +{ + int pos = searchenv(env, name); + + if (strchr(name, '=')) { + /* ('key=value'), insert of replace entry */ + if (pos >= env_nr) + env_nr++; + env[pos] = (char *) name; + } else if (pos < env_nr) { + /* otherwise ('key') remove existing entry */ + env_nr--; + memmove(&env[pos], &env[pos + 1], + (env_nr - pos) * sizeof(char *)); + env[env_nr] = NULL; + } + + return env_nr; +} + +static char **prep_childenv(const char *const *deltaenv) +{ + char **childenv; + int childenv_nr = 0, childenv_alloc = 0; + int i; + + for (i = 0; environ[i]; i++) + childenv_nr++; + for (i = 0; deltaenv && deltaenv[i]; i++) + childenv_alloc++; + /* Add one for the NULL termination */ + childenv_alloc += childenv_nr + 1; + + childenv = xcalloc(childenv_alloc, sizeof(char *)); + memcpy(childenv, environ, childenv_nr * sizeof(char *)); + + /* merge in deltaenv */ + for (i = 0; deltaenv && deltaenv[i]; i++) + childenv_nr = do_putenv(childenv, childenv_nr, deltaenv[i]); + + return childenv; +} + int start_command(struct child_process *cmd) { int need_in, need_out, need_err; @@ -365,12 +434,15 @@ int start_command(struct child_process *cmd) #ifndef GIT_WINDOWS_NATIVE { int notify_pipe[2]; + char **childenv; FILE *child_err = NULL; struct argv_array argv = ARGV_ARRAY_INIT; if (pipe(notify_pipe)) notify_pipe[0] = notify_pipe[1] = -1; + childenv = prep_childenv(cmd->env); + if (cmd->no_stderr || need_err) { int child_err_fd = dup(2); set_cloexec(child_err_fd); @@ -437,16 +509,9 @@ int start_command(struct child_process *cmd) if (cmd->dir && chdir(cmd->dir)) die_errno("exec '%s': cd to '%s' failed", cmd->argv[0], cmd->dir); - if (cmd->env) { - for (; *cmd->env; cmd->env++) { - if (strchr(*cmd->env, '=')) - putenv((char *)*cmd->env); - else - unsetenv(*cmd->env); - } - } - sane_execvpe(argv.argv[0], (char *const*) argv.argv, NULL); + sane_execvpe(argv.argv[0], (char *const*) argv.argv, + (char *const*) childenv); if (errno == ENOENT) { if (!cmd->silent_exec_failure) @@ -483,6 +548,7 @@ int start_command(struct child_process *cmd) if (child_err) fclose(child_err); + free(childenv); argv_array_clear(&argv); } #else -- 2.12.2.715.g7642488e1d-goog