1/* vi: set sw=4 ts=4: */ 2/* 3 * Utility routines. 4 * 5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> 6 * 7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. 8 */ 9 10#include "libbb.h" 11 12ssize_t safe_read(int fd, void *buf, size_t count) 13{ 14 ssize_t n; 15 16 do { 17 n = read(fd, buf, count); 18 } while (n < 0 && errno == EINTR); 19 20 return n; 21} 22 23/* 24 * Read all of the supplied buffer from a file. 25 * This does multiple reads as necessary. 26 * Returns the amount read, or -1 on an error. 27 * A short read is returned on an end of file. 28 */ 29ssize_t full_read(int fd, void *buf, size_t len) 30{ 31 ssize_t cc; 32 ssize_t total; 33 34 total = 0; 35 36 while (len) { 37 cc = safe_read(fd, buf, len); 38 39 if (cc < 0) 40 return cc; /* read() returns -1 on failure. */ 41 if (cc == 0) 42 break; 43 buf = ((char *)buf) + cc; 44 total += cc; 45 len -= cc; 46 } 47 48 return total; 49} 50 51// Die with an error message if we can't read the entire buffer. 52void xread(int fd, void *buf, size_t count) 53{ 54 if (count) { 55 ssize_t size = full_read(fd, buf, count); 56 if (size != count) 57 bb_error_msg_and_die("short read"); 58 } 59} 60 61// Die with an error message if we can't read one character. 62unsigned char xread_char(int fd) 63{ 64 char tmp; 65 xread(fd, &tmp, 1); 66 return tmp; 67} 68 69// Read one line a-la fgets. Works only on seekable streams 70char *reads(int fd, char *buffer, size_t size) 71{ 72 char *p; 73 74 if (size < 2) 75 return NULL; 76 size = full_read(fd, buffer, size-1); 77 if ((ssize_t)size <= 0) 78 return NULL; 79 80 buffer[size] = '\0'; 81 p = strchr(buffer, '\n'); 82 if (p) { 83 off_t offset; 84 *p++ = '\0'; 85 // avoid incorrect (unsigned) widening 86 offset = (off_t)(p-buffer) - (off_t)size; 87 // set fd position right after '\n' 88 if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1) 89 return NULL; 90 } 91 return buffer; 92} 93 94// Read one line a-la fgets. Reads byte-by-byte. 95// Useful when it is important to not read ahead. 96char *xmalloc_reads(int fd, char *buf) 97{ 98 char *p; 99 int sz = buf ? strlen(buf) : 0; 100 101 goto jump_in; 102 while (1) { 103 if (p - buf == sz) { 104 jump_in: 105 buf = xrealloc(buf, sz + 128); 106 p = buf + sz; 107 sz += 128; 108 } 109 if (safe_read(fd, p, 1) != 1) { /* EOF/error */ 110 if (p == buf) { 111 /* we read nothing [and buf was NULL initially] */ 112 free(buf); 113 return NULL; 114 } 115 break; 116 } 117 if (*p == '\n') 118 break; 119 p++; 120 } 121 *p++ = '\0'; 122 return xrealloc(buf, p - buf); 123} 124 125ssize_t read_close(int fd, void *buf, size_t size) 126{ 127 /*int e;*/ 128 size = full_read(fd, buf, size); 129 /*e = errno;*/ 130 close(fd); 131 /*errno = e;*/ 132 return size; 133} 134 135ssize_t open_read_close(const char *filename, void *buf, size_t size) 136{ 137 int fd = open(filename, O_RDONLY); 138 if (fd < 0) 139 return fd; 140 return read_close(fd, buf, size); 141} 142 143// Read (potentially big) files in one go. File size is estimated by 144// lseek to end. 145void *xmalloc_open_read_close(const char *filename, size_t *sizep) 146{ 147 char *buf; 148 size_t size = sizep ? *sizep : INT_MAX; 149 int fd; 150 off_t len; 151 152 fd = xopen(filename, O_RDONLY); 153 /* /proc/N/stat files report len 0 here */ 154 /* In order to make such files readable, we add small const */ 155 len = xlseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */ 156 xlseek(fd, 0, SEEK_SET); 157 if (len < size) 158 size = len; 159 buf = xmalloc(size + 1); 160 size = read_close(fd, buf, size); 161 if ((ssize_t)size < 0) 162 bb_perror_msg_and_die("'%s'", filename); 163 xrealloc(buf, size + 1); 164 buf[size] = '\0'; 165 if (sizep) 166 *sizep = size; 167 return buf; 168} 169