1 /* $OpenBSD: cmd_exec.c,v 1.8 2010/07/19 19:46:43 espie Exp $ */ 2 /* 3 * Copyright (c) 2001 Marc Espie. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT AND CONTRIBUTORS 15 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 16 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 17 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OPENBSD 18 * PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 19 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 20 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 #include <sys/wait.h> 29 #include <errno.h> 30 #include <stdio.h> 31 #include <unistd.h> 32 #include "config.h" 33 #include "defines.h" 34 #include "cmd_exec.h" 35 #include "buf.h" 36 #include "memory.h" 37 #include "pathnames.h" 38 39 char * 40 Cmd_Exec(const char *cmd, char **err) 41 { 42 char *args[4]; /* Args for invoking the shell */ 43 int fds[2]; /* Pipe streams */ 44 pid_t cpid; /* Child PID */ 45 pid_t pid; /* PID from wait() */ 46 char *result; /* Result */ 47 int status; /* Command exit status */ 48 BUFFER buf; /* Buffer to store the result. */ 49 char *cp; /* Pointer into result. */ 50 ssize_t cc; /* Characters read from pipe. */ 51 size_t length; /* Total length of result. */ 52 53 54 *err = NULL; 55 56 /* Set up arguments for the shell. */ 57 args[0] = "sh"; 58 args[1] = "-c"; 59 args[2] = (char *)cmd; 60 args[3] = NULL; 61 62 /* Open a pipe for retrieving shell's output. */ 63 if (pipe(fds) == -1) { 64 *err = "Couldn't create pipe for \"%s\""; 65 goto bad; 66 } 67 68 /* Fork */ 69 switch (cpid = fork()) { 70 case 0: 71 /* Close input side of pipe */ 72 (void)close(fds[0]); 73 74 /* Duplicate the output stream to the shell's output, then 75 * shut the extra thing down. Note we don't fetch the error 76 * stream: user can use redirection to grab it as this goes 77 * through /bin/sh. 78 */ 79 if (fds[1] != 1) { 80 (void)dup2(fds[1], 1); 81 (void)close(fds[1]); 82 } 83 84 (void)execv(_PATH_BSHELL, args); 85 _exit(1); 86 /*NOTREACHED*/ 87 88 case -1: 89 *err = "Couldn't exec \"%s\""; 90 goto bad; 91 92 default: 93 /* No need for the writing half. */ 94 (void)close(fds[1]); 95 96 Buf_Init(&buf, MAKE_BSIZE); 97 98 do { 99 char grab[BUFSIZ]; 100 101 cc = read(fds[0], grab, sizeof(grab)); 102 if (cc > 0) 103 Buf_AddChars(&buf, cc, grab); 104 } while (cc > 0 || (cc == -1 && errno == EINTR)); 105 106 /* Close the input side of the pipe. */ 107 (void)close(fds[0]); 108 109 /* Wait for the child to exit. */ 110 while ((pid = wait(&status)) != cpid && pid >= 0) 111 continue; 112 113 if (cc == -1) 114 *err = "Couldn't read shell's output for \"%s\""; 115 116 if (status) 117 *err = "\"%s\" returned non-zero status"; 118 119 length = Buf_Size(&buf); 120 result = Buf_Retrieve(&buf); 121 122 /* The result is null terminated, Convert newlines to spaces. */ 123 cp = result + length - 1; 124 125 if (cp >= result && *cp == '\n') 126 /* A final newline is just stripped. */ 127 *cp-- = '\0'; 128 129 while (cp >= result) { 130 if (*cp == '\n') 131 *cp = ' '; 132 cp--; 133 } 134 break; 135 } 136 return result; 137 bad: 138 return estrdup(""); 139 } 140 141