toaruos/apps/kcmdline.c

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/* vim: tabstop=4 shiftwidth=4 noexpandtab
* This file is part of ToaruOS and is released under the terms
* of the NCSA / University of Illinois License - see LICENSE.md
* Copyright (C) 2018 K. Lange
*
* kcmdline - Parse /proc/cmdline usefully.
*
* Parses /proc/cmdline and provides an interface for querying
* whether an argument was present, and its value if applicable.
*
* Also converts ASCII field separators to spaces so that cmdline
* arguments can have spaces in them.
*
* Useful for shell scripts.
*
* TODO: This should probably be a library we can use in other
* applications...
*/
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <toaru/hashmap.h>
hashmap_t * args_map = NULL;
int tokenize(char * str, char * sep, char **buf) {
char * pch_i;
char * save_i;
int argc = 0;
pch_i = strtok_r(str,sep,&save_i);
if (!pch_i) { return 0; }
while (pch_i != NULL) {
buf[argc] = (char *)pch_i;
++argc;
pch_i = strtok_r(NULL,sep,&save_i);
}
buf[argc] = NULL;
return argc;
}
void args_parse(char * _arg) {
char * arg = strdup(_arg);
char * argv[1024];
int argc = tokenize(arg, " ", argv);
for (int i = 0; i < argc; ++i) {
char * c = strdup(argv[i]);
char * name;
char * value;
name = c;
value = NULL;
/* Find the first = and replace it with a null */
char * v = c;
while (*v) {
if (*v == '=') {
*v = '\0';
v++;
value = v;
char * tmp = value;
/* scan it for \037 and replace with spaces */
while (*tmp) {
if (*tmp == '\037') {
*tmp = ' ';
}
tmp++;
}
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goto _break;
}
v++;
}
_break:
hashmap_set(args_map, name, value);
}
free(arg);
}
void show_usage(int argc, char * argv[]) {
printf(
"kcmdline - query the kernel command line\n"
"\n"
"usage: %s -g ARG...\n"
" %s -q ARG...\n"
"\n"
" -g \033[3mprint the value for the requested argument\033[0m\n"
" -q \033[3mquery whether the requested argument is present (0 = yes)\033[0m\n"
" -? \033[3mshow this help text\033[0m\n"
"\n", argv[0], argv[0]);
}
int main(int argc, char * argv[]) {
/* Open */
FILE * f = fopen("/proc/cmdline", "r");
if (!f) return 1;
/* Read */
char * cmdline = malloc(4096); /* cmdline can't be longer than that */
memset(cmdline, 0, 4096);
size_t size = fread(cmdline, 1, 4096, f);
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if (cmdline[size-1] == '\n') cmdline[size-1] = '\0';
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fclose(f);
/* Parse */
args_map = hashmap_create(10);
args_parse(cmdline);
/* Figure out what we're doing */
int opt;
while ((opt = getopt(argc, argv, "?g:q:s")) != -1) {
switch (opt) {
case 'g':
if (hashmap_has(args_map, optarg)) {
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char * tmp = (char*)hashmap_get(args_map, optarg);
if (!tmp) {
printf("%s\n", optarg); /* special case = present but not set should yield name of variable */
} else {
printf("%s\n", tmp);
}
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return 0;
} else {
return 1;
}
case 'q':
return !hashmap_has(args_map,optarg);
case 's':
return size;
case '?':
show_usage(argc, argv);
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return 1;
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}
}
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fprintf(stdout, "%s\n", cmdline);
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}