1 /* $OpenBSD: cmd_exec.c,v 1.10 2016/03/28 11:27:37 chl 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 char *result; /* Result */ 46 int status; /* Command exit status */ 47 BUFFER buf; /* Buffer to store the result. */ 48 char *cp; /* Pointer into result. */ 49 ssize_t cc; /* Characters read from pipe. */ 50 size_t length; /* Total length of result. */ 51 52 53 *err = NULL; 54 55 /* Set up arguments for the shell. */ 56 args[0] = "sh"; 57 args[1] = "-c"; 58 args[2] = (char *)cmd; 59 args[3] = NULL; 60 61 /* Open a pipe for retrieving shell's output. */ 62 if (pipe(fds) == -1) { 63 *err = "Couldn't create pipe for \"%s\""; 64 goto bad; 65 } 66 67 /* Fork */ 68 switch (cpid = fork()) { 69 case 0: 70 /* Close input side of pipe */ 71 (void)close(fds[0]); 72 73 /* Duplicate the output stream to the shell's output, then 74 * shut the extra thing down. Note we don't fetch the error 75 * stream: user can use redirection to grab it as this goes 76 * through /bin/sh. 77 */ 78 if (fds[1] != 1) { 79 (void)dup2(fds[1], 1); 80 (void)close(fds[1]); 81 } 82 83 (void)execv(_PATH_BSHELL, args); 84 _exit(1); 85 /*NOTREACHED*/ 86 87 case -1: 88 *err = "Couldn't exec \"%s\""; 89 goto bad; 90 91 default: 92 /* No need for the writing half. */ 93 (void)close(fds[1]); 94 95 Buf_Init(&buf, MAKE_BSIZE); 96 97 do { 98 char grab[BUFSIZ]; 99 100 cc = read(fds[0], grab, sizeof(grab)); 101 if (cc > 0) 102 Buf_AddChars(&buf, cc, grab); 103 } while (cc > 0 || (cc == -1 && errno == EINTR)); 104 105 /* Close the input side of the pipe. */ 106 (void)close(fds[0]); 107 108 /* Wait for the child to exit. */ 109 while (waitpid(cpid, &status, 0) == -1 && errno == EINTR) 110 continue; 111 112 if (cc == -1) 113 *err = "Couldn't read shell's output for \"%s\""; 114 115 if (status) 116 *err = "\"%s\" returned non-zero status"; 117 118 length = Buf_Size(&buf); 119 result = Buf_Retrieve(&buf); 120 121 /* The result is null terminated, Convert newlines to spaces. */ 122 cp = result + length - 1; 123 124 if (cp >= result && *cp == '\n') 125 /* A final newline is just stripped. */ 126 *cp-- = '\0'; 127 128 while (cp >= result) { 129 if (*cp == '\n') 130 *cp = ' '; 131 cp--; 132 } 133 break; 134 } 135 return result; 136 bad: 137 return estrdup(""); 138 } 139 140