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	sysctl.c - ubase - suckless linux base utils
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	---
	sysctl.c (3285B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <fcntl.h>
	3 #include <limits.h>
	4 #include <stdio.h>
	5 #include <stdlib.h>
	6 #include <string.h>
	7 #include <unistd.h>
	8
	9 #include "text.h"
	10 #include "util.h"
	11
	12 static void
	13 replacestr(char *s, int a, int b)
	14 {
	15 for (; *s; s++)
	16 if (*s == a)
	17 *s = b;
	18 }
	19
	20 static int
	21 getsysctl(char variable, char *value)
	22 {
	23 char path[PATH_MAX];
	24 char *p;
	25 char buf, tmp, c;
	26 int fd;
	27 ssize_t n;
	28 size_t sz, i;
	29
	30 replacestr(variable, '.', '/');
	31
	32 strlcpy(path, "/proc/sys/", sizeof(path));
	33 if (strlcat(path, variable, sizeof(path)) >= sizeof(path)) {
	34 replacestr(variable, '/', '.');
	35 return -1;
	36 }
	37
	38 replacestr(variable, '/', '.');
	39
	40 fd = open(path, O_RDONLY);
	41 if (fd < 0)
	42 return -1;
	43
	44 i = 0;
	45 sz = 1;
	46 buf = NULL;
	47 while (1) {
	48 n = read(fd, &c, 1);
	49 if (n < 0) {
	50 close(fd);
	51 free(buf);
	52 return -1;
	53 }
	54 if (n == 0)
	55 break;
	56 if (i == sz - 1) {
	57 sz *= 2;
	58 tmp = realloc(buf, sz);
	59 if (!tmp) {
	60 close(fd);
	61 free(buf);
	62 return -1;
	63 }
	64 buf = tmp;
	65 }
	66 buf[i++] = c;
	67 }
	68 buf[i] = '\0';
	69
	70 p = strrchr(buf, '\n');
	71 if (p)
	72 *p = '\0';
	73
	74 *value = buf;
	75
	76 close(fd);
	77
	78 return 0;
	79 }
	80
	81 static int
	82 setsysctl(char variable, char value)
	83 {
	84 char path[PATH_MAX];
	85 int fd;
	86 ssize_t n;
	87
	88 replacestr(variable, '.', '/');
	89
	90 strlcpy(path, "/proc/sys/", sizeof(path));
	91 if (strlcat(path, variable, sizeof(path)) >= sizeof(path)) {
	92 replacestr(variable, '/', '.');
	93 return -1;
	94 }
	95
	96 replacestr(variable, '/', '.');
	97
	98 fd = open(path, O_WRONLY);
	99 if (fd < 0)
	100 return -1;
	101
	102 n = write(fd, value, strlen(value));
	103 if ((size_t)n != strlen(value)) {
	104 close(fd);
	105 return -1;
	106 }
	107
	108 close(fd);
	109
	110 return 0;
	111 }
	112
	113 static int
	114 parsepair(char *pair)
	115 {
	116 char *p;
	117 char *variable;
	118 char *value;
	119
	120 for (p = pair; *p; p++) {
	121 if (p[0] == '.' && p[1] == '.') {
	122 weprintf("malformed input: %s\n", pair);
	123 return -1;
	124 }
	125 }
	126 p = strchr(pair, '=');
	127 if (p) {
	128 if (p[1] == '\0') {
	129 weprintf("malformed input: %s\n", pair);
	130 return -1;
	131 }
	132 *p = '\0';
	133 value = &p[1];
	134 } else {
	135 value = NULL;
	136 }
	137 variable = pair;
	138 if (value) {
	139 if (setsysctl(variable, value) < 0) {
	140 weprintf("failed to set sysctl for %s\n", variab…
	141 return -1;
	142 }
	143 } else {
	144 if (getsysctl(variable, &value) < 0) {
	145 weprintf("failed to get sysctl for %s\n", variab…
	146 return -1;
	147 }
	148 printf("%s = %s\n", variable, value);
	149 free(value);
	150 }
	151
	152 return 0;
	153 }
	154
	155 static void
	156 usage(void)
	157 {
	158 eprintf("usage: %s [-p file] variable[=value]...\n", argv0);
	159 }
	160
	161 int
	162 main(int argc, char *argv[])
	163 {
	164 FILE *fp;
	165 char buf = NULL, p;
	166 char *file = NULL;
	167 size_t size = 0;
	168 int i;
	169 int r = 0;
	170
	171 ARGBEGIN {
	172 case 'p':
	173 file = EARGF(usage());
	174 break;
	175 default:
	176 usage();
	177 } ARGEND;
	178
	179 if (!file && argc < 1)
	180 usage();
	181
	182 if (!file) {
	183 for (i = 0; i < argc; i++)
	184 if (parsepair(argv[i]) < 0)
	185 r = 1;
	186 } else {
	187 fp = fopen(file, "r");
	188 if (!fp)
	189 eprintf("fopen %s:", file);
	190 while (agetline(&buf, &size, fp) != -1) {
	191 p = buf;
	192 for (p = buf; p == ' ' \|\| p == '\t'; p++)
	193 ;
	194 if (p == '#' \|\| p == '\n')
	195 continue;
	196 for (p = buf; *p; p++) {
	197 if (*p == '\n') {
	198 *p = '\0';
	199 break;
	200 }
	201 }
	202 p = buf;
	203 if (parsepair(p) < 0)
	204 r = 1;
	205 }
	206 if (ferror(fp))
	207 eprintf("%s: read error:", file);
	208 free(buf);
	209 fclose(fp);
	210 }
	211
	212 return r;
	213 }