Simple ACPI/PMU data extraction routine

[Richard Hughes]

I've just quickly written this quick routine for getting values such as
"brightness:    5" from ACPI and PMU procfs entries.

ACPI confuses things by sometimes appending a newline, and having a
variable amount of spacing (sometimes tabs, sometimes spaces). I've not
tested it on a PMU file, but there's no reason for it not to work.

I'll paste my sample code here, to see if you can see any obv. oversights
or security faux-pas. Its just past midnight here, so I'll blame that if
the code is bad.

Again, comments as usual please.

#include <stdio.h>

/* finds specific variables in files that have
    incorrect string value:  nothing
    correct string value:    answer
    incorrect string value:  nothing
   type entries, typically from ACPI or PMU config files
*/
int getprocfsvalue(char* filename, char* search, char* result)
{
	int i, length;
	char templine[128]; 
	FILE *file;
	file = fopen(filename, "r");

	/* file not exists */
	if (file==NULL) return -1;

	/* find line */
	while (fgets(templine, 128, file) != NULL) {
		length = strlen(search);
		if (strncmp(search, templine, length) == 0) {
			/* turn first new line into null, as ACPI appends \n */
			for(i=0;i<128-length;i++)
				if(templine[i+length] == '\n') {
					templine[i+length] = 0;
					break;
				}
			/* eat leading whitespace, which can be \t or space */
			for(i=0;i<128-length;i++) {
				if((templine[i+length] != ' ') && (templine[i+length] != '\t'))
					break;
			}
			/* copy substring into result */
			strncpy(result, templine+length+i, 128);
			/* shortcut loop */
			break;
		}
	}

	fclose(file);
	return 1;
}

int main() {
	char filename[1024];
	char search[128];
	char result[128]; 

	strncpy(filename, "/proc/acpi/battery/BAT1/state", 1024);
	strncpy(search, "present rate:", 128);

	getprocfsvalue(filename, search, result);
	printf("[%s]\n", result);

	return 0;
}


-- 

http://www.hughsie.com/PUBLIC-KEY


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