OpenWrt – Blame information for rev 1
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Rev | Author | Line No. | Line |
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1 | office | 1 | --- /dev/null |
2 | +++ b/miscutils/lock.c |
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3 | @@ -0,0 +1,155 @@ |
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4 | +/* |
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5 | + * Copyright (C) 2006 Felix Fietkau <nbd@nbd.name> |
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6 | + * |
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7 | + * This is free software, licensed under the GNU General Public License v2. |
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8 | + */ |
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9 | + |
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10 | +//config:config LOCK |
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11 | +//config: bool "lock" |
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12 | +//config: default n |
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13 | +//config: help |
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14 | +//config: Small utility for using locks in scripts |
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15 | + |
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16 | +//applet:IF_LOCK(APPLET(lock, BB_DIR_BIN, BB_SUID_DROP)) |
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17 | + |
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18 | +//kbuild:lib-$(CONFIG_LOCK) += lock.o |
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19 | + |
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20 | +//usage:#define lock_trivial_usage NOUSAGE_STR |
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21 | +//usage:#define lock_full_usage "" |
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22 | + |
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23 | +#include <sys/types.h> |
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24 | +#include <sys/file.h> |
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25 | +#include <sys/stat.h> |
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26 | +#include <signal.h> |
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27 | +#include <fcntl.h> |
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28 | +#include <unistd.h> |
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29 | +#include <stdio.h> |
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30 | +#include "busybox.h" |
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31 | + |
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32 | +static int unlock = 0; |
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33 | +static int shared = 0; |
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34 | +static int waitonly = 0; |
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35 | +static int try_lock = 0; |
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36 | +static int fd; |
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37 | +static char *file; |
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38 | + |
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39 | +static void usage(char *name) |
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40 | +{ |
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41 | + fprintf(stderr, "Usage: %s [-suw] <filename>\n" |
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42 | + " -s Use shared locking\n" |
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43 | + " -u Unlock\n" |
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44 | + " -w Wait for the lock to become free, don't acquire lock\n" |
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45 | + " -n Don't wait for the lock to become free. Fail with exit code\n" |
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46 | + "\n", name); |
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47 | + exit(1); |
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48 | +} |
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49 | + |
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50 | +static void exit_unlock(int sig) |
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51 | +{ |
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52 | + flock(fd, LOCK_UN); |
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53 | + exit(0); |
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54 | +} |
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55 | + |
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56 | +static int do_unlock(void) |
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57 | +{ |
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58 | + FILE *f; |
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59 | + int i; |
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60 | + |
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61 | + if ((f = fopen(file, "r")) == NULL) |
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62 | + return 0; |
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63 | + |
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64 | + fscanf(f, "%d", &i); |
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65 | + if (i > 0) |
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66 | + kill(i, SIGTERM); |
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67 | + |
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68 | + fclose(f); |
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69 | + |
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70 | + return 0; |
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71 | +} |
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72 | + |
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73 | +static int do_lock(void) |
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74 | +{ |
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75 | + int pid; |
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76 | + int flags; |
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77 | + char pidstr[8]; |
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78 | + |
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79 | + if ((fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0700)) < 0) { |
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80 | + if ((fd = open(file, O_RDWR)) < 0) { |
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81 | + fprintf(stderr, "Can't open %s\n", file); |
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82 | + return 1; |
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83 | + } |
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84 | + } |
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85 | + |
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86 | + flags = shared ? LOCK_SH : LOCK_EX; |
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87 | + flags |= try_lock ? LOCK_NB : 0; |
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88 | + |
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89 | + if (flock(fd, flags) < 0) { |
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90 | + fprintf(stderr, "Can't lock %s\n", file); |
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91 | + return 1; |
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92 | + } |
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93 | + |
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94 | + pid = fork(); |
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95 | + |
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96 | + if (pid < 0) |
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97 | + return -1; |
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98 | + |
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99 | + if (pid == 0) { |
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100 | + signal(SIGKILL, exit_unlock); |
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101 | + signal(SIGTERM, exit_unlock); |
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102 | + signal(SIGINT, exit_unlock); |
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103 | + if (waitonly) |
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104 | + exit_unlock(0); |
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105 | + else |
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106 | + while (1) |
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107 | + sleep(1); |
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108 | + } else { |
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109 | + if (!waitonly) { |
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110 | + lseek(fd, 0, SEEK_SET); |
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111 | + ftruncate(fd, 0); |
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112 | + sprintf(pidstr, "%d\n", pid); |
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113 | + write(fd, pidstr, strlen(pidstr)); |
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114 | + close(fd); |
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115 | + } |
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116 | + |
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117 | + return 0; |
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118 | + } |
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119 | + return 0; |
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120 | +} |
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121 | + |
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122 | +int lock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
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123 | +int lock_main(int argc, char **argv) |
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124 | +{ |
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125 | + char **args = &argv[1]; |
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126 | + int c = argc - 1; |
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127 | + |
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128 | + while ((*args != NULL) && (*args)[0] == '-') { |
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129 | + char *ch = *args; |
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130 | + while (*(++ch) > 0) { |
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131 | + switch(*ch) { |
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132 | + case 'w': |
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133 | + waitonly = 1; |
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134 | + break; |
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135 | + case 's': |
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136 | + shared = 1; |
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137 | + break; |
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138 | + case 'u': |
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139 | + unlock = 1; |
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140 | + break; |
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141 | + case 'n': |
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142 | + try_lock = 1; |
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143 | + break; |
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144 | + } |
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145 | + } |
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146 | + c--; |
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147 | + args++; |
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148 | + } |
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149 | + |
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150 | + if (c != 1) |
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151 | + usage(argv[0]); |
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152 | + |
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153 | + file = *args; |
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154 | + if (unlock) |
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155 | + return do_unlock(); |
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156 | + else |
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157 | + return do_lock(); |
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158 | +} |