fileupd.c revision 20253
1/*- 2 * Copyright (c) 1996 by David L. Nugent <davidn@blaze.net.au>. 3 * All rights reserved. 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 as 10 * the first lines of this file unmodified. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by David L. Nugent. 17 * 4. The name of the author may not be used to endorse or promote products 18 * derived from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE DAVID L. NUGENT ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL DAVID L. NUGENT BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * $Id$ 33 */ 34 35#include <stdio.h> 36#include <fcntl.h> 37#include <stdlib.h> 38#include <string.h> 39#include <sys/types.h> 40#include <sys/stat.h> 41#include <sys/param.h> 42#include <errno.h> 43#include <unistd.h> 44 45#include "pwupd.h" 46 47int 48fileupdate(char const * filename, mode_t fmode, char const * newline, char const * prefix, int pfxlen, int updmode) 49{ 50 int rc = 0; 51 52 if (pfxlen <= 1) 53 errno = EINVAL; 54 else { 55 int infd = open(filename, O_RDWR | O_CREAT | O_EXLOCK, fmode); 56 57 if (infd != -1) { 58 FILE *infp = fdopen(infd, "r+"); 59 60 if (infp == NULL) 61 close(infd); 62 else { 63 int outfd; 64 char file[MAXPATHLEN]; 65 66 strcpy(file, filename); 67 strcat(file, ".new"); 68 outfd = open(file, O_RDWR | O_CREAT | O_TRUNC | O_EXLOCK, fmode); 69 if (outfd != -1) { 70 FILE *outfp = fdopen(outfd, "w+"); 71 72 if (outfp == NULL) 73 close(outfd); 74 else { 75 int updated = UPD_CREATE; 76 char line[2048]; 77 78 while (fgets(line, sizeof(line), infp) != NULL) { 79 char *p = strchr(line, '\n'); 80 81 if (p == NULL) { /* Line too long */ 82 int ch; 83 84 fputs(line, outfp); 85 while ((ch = fgetc(infp)) != EOF) { 86 fputc(ch, outfp); 87 if (ch == '\n') 88 break; 89 } 90 continue; 91 } 92 if (*line != '#' && *line != '\n') { 93 if (!updated && strncmp(line, prefix, pfxlen) == 0) { 94 updated = updmode == UPD_REPLACE ? UPD_REPLACE : UPD_DELETE; 95 96 /* 97 * Only actually write changes if updating 98 */ 99 if (updmode == UPD_REPLACE) 100 strcpy(line, newline); 101 else if (updmode == UPD_DELETE) 102 continue; 103 } 104 } 105 fputs(line, outfp); 106 } 107 108 /* 109 * Now, we need to decide what to do: If we are in 110 * update mode, and no record was updated, then error If 111 * we are in insert mode, and record already exists, 112 * then error 113 */ 114 if (updmode != updated) 115 errno = (updmode == UPD_CREATE) ? EEXIST : ENOENT; 116 else { 117 118 /* 119 * If adding a new record, append it to the end 120 */ 121 if (updmode == UPD_CREATE) 122 fputs(newline, outfp); 123 124 /* 125 * Flush the file and check for the result 126 */ 127 rc = fflush(outfp) != EOF; 128 if (rc) { 129 130 /* 131 * Copy data back into the 132 * original file and truncate 133 */ 134 rewind(infp); 135 rewind(outfp); 136 while (fgets(line, sizeof(line), outfp) != NULL) 137 fputs(line, infp); 138 139 /* 140 * This is a gross hack, but we may have 141 * corrupted the original file 142 * Unfortunately, it will lose the inode. 143 */ 144 if (fflush(infp) == EOF || ferror(infp)) 145 rc = rename(file, filename) == 0; 146 else 147 ftruncate(infd, ftell(infp)); 148 } 149 } 150 fclose(outfp); 151 } 152 remove(file); 153 } 154 fclose(infp); 155 } 156 } 157 } 158 return rc; 159} 160