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/* sysctl.c - A utility to read and manipulate the sysctl parameters.
*
* Copyright 2014 Bilal Qureshi <bilal.jmi@gmail.com>
* Copyright 2014 Kyungwan Han <asura321@gmail.com>
*
* No Standard
USE_SYSCTL(NEWTOY(sysctl, "^neNqwpaA[!ap][!aq][!aw][+aA]", TOYFLAG_SBIN))
config SYSCTL
bool "sysctl"
default y
help
usage: sysctl [-aAeNnqw] [-p [FILE] | KEY[=VALUE]...]
Read/write system control data (under /proc/sys).
-a,A Show all values
-e Don't warn about unknown keys
-N Don't print key values
-n Don't print key names
-p Read values from FILE (default /etc/sysctl.conf)
-q Don't show value after write
-w Only write values (object to reading)
*/
#define FOR_sysctl
#include "toys.h"
// Null terminate at =, return value
static char *split_key(char *key)
{
char *value = strchr(key, '=');
if (value) *(value++)=0;
return value;
}
static void replace_char(char *str, char old, char new)
{
for (; *str; str++) if (*str == old) *str = new;
}
static void key_error(char *key)
{
if (errno == ENOENT) {
if (!(toys.optflags & FLAG_e)) error_msg("unknown key '%s'", key);
} else perror_msg("key '%s'", key);
}
static int write_key(char *path, char *key, char *value)
{
int fd = open(path, O_WRONLY);
if (fd < 0) {
key_error(key);
return 0;
}
xwrite(fd, value, strlen(value));
xclose(fd);
return 1;
}
// Display all keys under a path
static int do_show_keys(struct dirtree *dt)
{
char *path, *data, *key;
if (!dirtree_notdotdot(dt)) return 0; // Skip . and ..
if (S_ISDIR(dt->st.st_mode)) return DIRTREE_RECURSE;
path = dirtree_path(dt, 0);
data = readfile(path, 0, 0);
replace_char(key = path + 10, '/', '.'); // skip "/proc/sys/"
if (!data) key_error(key);
else {
// Print the parts that aren't switched off by flags.
if (!(toys.optflags & FLAG_n)) xprintf("%s", key);
if (!(toys.optflags & (FLAG_N|FLAG_n))) xprintf(" = ");
for (key = data+strlen(data); key > data && isspace(*--key); *key = 0);
if (!(toys.optflags & FLAG_N)) xprintf("%s", data);
if ((toys.optflags & (FLAG_N|FLAG_n)) != (FLAG_N|FLAG_n)) xputc('\n');
}
free(data);
free(path);
return 0;
}
// Read/write entries under a key. Accepts "key=value" in key if !value
static void process_key(char *key, char *value)
{
char *path;
if (!value) value = split_key(key);
if ((toys.optflags & FLAG_w) && !value) {
error_msg("'%s' not key=value", key);
return;
}
path = xmprintf("/proc/sys/%s", key);
replace_char(path, '.', '/');
// Note: failure to assign to a non-leaf node suppresses the display.
if (!(value && (!write_key(path, key, value) || (toys.optflags & FLAG_q)))) {
if (!access(path, R_OK)) dirtree_read(path, do_show_keys);
else key_error(key);
}
free(path);
}
void sysctl_main()
{
char **args = 0;
// Display all keys
if (toys.optflags & FLAG_a) dirtree_read("/proc/sys", do_show_keys);
// read file
else if (toys.optflags & FLAG_p) {
FILE *fp = xfopen(*toys.optargs ? *toys.optargs : "/etc/sysctl.conf", "r");
size_t len;
for (;;) {
char *line = 0, *key, *val;
if (-1 == (len = getline(&line, &len, fp))) break;
key = line;
while (isspace(*key)) key++;
if (*key == '#' || *key == ';' || !*key) continue;
while (len && isspace(line[len-1])) line[--len] = 0;
if (!(val = split_key(line))) {
error_msg("'%s' not key=value", line);
continue;
}
// Trim whitespace around =
len = (val-line)-1;
while (len && isspace(line[len-1])) line[--len] = 0;
while (isspace(*val)) val++;;
process_key(key, val);
free(line);
}
fclose(fp);
// Loop through arguments, displaying or assigning as appropriate
} else {
if (!*toys.optargs) help_exit("Needs 1 arg");
for (args = toys.optargs; *args; args++) process_key(*args, 0);
}
}
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