mirror of
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e74acd59a5
the newly allocated FILE * has not yet leaked to the application and is only visible to stdio internals until popen returns. since we do not change any fields of the structure observed by libc internals, only the pipe_pid member, locking is not necessary.
55 lines
1.1 KiB
C
55 lines
1.1 KiB
C
#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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#include <spawn.h>
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#include "stdio_impl.h"
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#include "syscall.h"
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extern char **__environ;
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FILE *popen(const char *cmd, const char *mode)
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{
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int p[2], op, e;
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pid_t pid;
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FILE *f;
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posix_spawn_file_actions_t fa;
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if (*mode == 'r') {
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op = 0;
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} else if (*mode == 'w') {
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op = 1;
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} else {
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errno = EINVAL;
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return 0;
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}
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if (pipe2(p, O_CLOEXEC)) return NULL;
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f = fdopen(p[op], mode);
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if (!f) {
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__syscall(SYS_close, p[0]);
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__syscall(SYS_close, p[1]);
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return NULL;
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}
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e = ENOMEM;
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if (!posix_spawn_file_actions_init(&fa)) {
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if (!posix_spawn_file_actions_adddup2(&fa, p[1-op], 1-op)) {
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if (!(e = posix_spawn(&pid, "/bin/sh", &fa, 0,
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(char *[]){ "sh", "-c", (char *)cmd, 0 }, __environ))) {
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posix_spawn_file_actions_destroy(&fa);
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f->pipe_pid = pid;
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if (!strchr(mode, 'e'))
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fcntl(p[op], F_SETFD, 0);
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__syscall(SYS_close, p[1-op]);
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return f;
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}
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}
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posix_spawn_file_actions_destroy(&fa);
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}
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fclose(f);
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__syscall(SYS_close, p[1-op]);
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errno = e;
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return 0;
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}
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