5d774cce1d
execl(3) and its variants use a sentinel to terminate the variadic argument list, in the form of a null pointer constant of type pointer to char. POSIX mandates that NULL is a null pointer constant of type pointer to void, which is not of an equivalent type to that required by execl(3) and its variants, resulting in undefined behaviour. This commit casts all such instances of NULL to pointer to char type. For consistency, it also adds const-qualification to any such instances which had already been casted, and were not const-qualified.
152 lines
3.7 KiB
C
152 lines
3.7 KiB
C
/*
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* Copyright (c) 2013, 2014 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* stdio/popen.c
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* Pipe stream to or from a process.
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*/
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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typedef struct popen_struct
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{
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int flags;
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int fd;
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pid_t pid;
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} popen_t;
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static ssize_t popen_read(void* user, void* ptr, size_t size)
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{
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popen_t* info = (popen_t*) user;
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return read(info->fd, ptr, size);
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}
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static ssize_t popen_write(void* user, const void* ptr, size_t size)
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{
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popen_t* info = (popen_t*) user;
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return write(info->fd, ptr, size);
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}
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static off_t popen_seek(void* user, off_t offset, int whence)
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{
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(void) user;
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(void) offset;
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(void) whence;
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return errno = ESPIPE, -1;
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}
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static int popen_close(void* user)
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{
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popen_t* info = (popen_t*) user;
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if ( close(info->fd) < 0 )
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{
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// TODO: Should this return value be discarded?
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}
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int status;
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if ( waitpid(info->pid, &status, 0) < 0 )
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status = -1;
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free(info);
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return status;
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}
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static void popen_install(FILE* fp, popen_t* info)
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{
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fp->user = info;
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fp->read_func = popen_read;
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fp->write_func = popen_write;
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fp->seek_func = popen_seek;
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fp->close_func = popen_close;
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}
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FILE* popen(const char* command, const char* type)
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{
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int mode_flags = fparsemode(type);
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if ( mode_flags < 0 )
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return (FILE*) NULL;
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if ( mode_flags & ~(FILE_MODE_READ | FILE_MODE_WRITE | FILE_MODE_CLOEXEC |
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FILE_MODE_CREATE | FILE_MODE_BINARY | FILE_MODE_TRUNCATE) )
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return errno = EINVAL, (FILE*) NULL;
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bool reading = mode_flags & FILE_MODE_READ;
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bool writing = mode_flags & FILE_MODE_WRITE;
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if ( reading == writing )
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return errno = EINVAL, (FILE*) NULL;
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int used_end, unused_end, redirect_what;
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int pipefds[2];
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popen_t* info;
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FILE* fp;
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pid_t childpid;
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if ( !(info = (popen_t*) calloc(1, sizeof(popen_t))) )
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goto cleanup_out;
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if ( !(fp = fnewfile()) )
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goto cleanup_info;
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if ( pipe(pipefds) )
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goto cleanup_fp;
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if ( (childpid = fork()) < 0 )
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goto cleanup_pipes;
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if ( childpid )
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{
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used_end = writing ? 1 /*writing*/ : 0 /*reading*/;
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unused_end = writing ? 0 /*reading*/ : 1 /*writing*/;
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close(pipefds[unused_end]);
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if ( mode_flags & FILE_MODE_CLOEXEC )
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fcntl(pipefds[used_end], F_SETFL, FD_CLOEXEC);
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info->fd = pipefds[used_end];
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info->pid = childpid;
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popen_install(fp, info);
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fp->flags |= writing ? _FILE_WRITABLE : _FILE_READABLE;
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fp->fd = info->fd;
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return fp;
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}
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redirect_what = writing ? 0 /*stdin*/ : 1 /*stdout*/;
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used_end = writing ? 0 /*reading*/ : 1 /*writing*/;
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unused_end = writing ? 1 /*writing*/ : 0 /*reading*/;
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if ( dup2(pipefds[used_end], redirect_what) < 0 ||
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close(pipefds[used_end]) ||
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close(pipefds[unused_end]) )
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_exit(127);
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execlp("sh", "sh", "-c", command, (const char*) NULL);
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_exit(127);
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cleanup_pipes:
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close(pipefds[0]);
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close(pipefds[1]);
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cleanup_fp:
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fclose(fp);
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cleanup_info:
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free(info);
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cleanup_out:
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return NULL;
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}
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int pclose(FILE* fp)
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{
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return fclose(fp);
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}
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