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/*
* Copyright © 2009 by Daniel Friesel <derf@derf.homelinux.org>
* License: WTFPL <http://sam.zoy.org/wtfpl>
*
* Function policy: Fail early (use err/errx if something goes wrong)
*/
#include <err.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#define CMD_EVAL 1
#define CMD_LIST 2
#define CMD_RM 3
#define CMD_SAVE 4
#define PARAM_LENGTH 256
#define VALUE_LENGTH 1024
#define SCAN_FORMAT "%255s %1023[^\n]\n"
static FILE * store_open(char *file) {
struct stat finfo;
uid_t self_uid = geteuid();
FILE *fp = fopen(file, "r");
/*
* err() should be used here, but since envstore save may or may not have
* an existing store to work with, return NULL if there's no usable store.
*/
if (fp == NULL)
return NULL;
if (fstat(fileno(fp), &finfo) != 0)
err(EXIT_FAILURE, "Unable to verify store file permissions (%s)", file);
if (finfo.st_uid != self_uid)
errx(EXIT_FAILURE, "Store file '%s' is insecure (must be owned by you, not uid %d)", file, finfo.st_uid);
if ((finfo.st_mode & 077) > 0)
errx(EXIT_FAILURE, "Store file '%s' has insecure permissions %04o (recommended: 0600)", file, finfo.st_mode & 07777);
return fp;
}
static char * new_filename(char *file) {
char *new_file = malloc(strlen(file) + 5);
if (new_file == NULL)
err(EXIT_FAILURE, "malloc");
if (snprintf(new_file, strlen(file) + 5, "%s.tmp", file) < 3)
err(EXIT_FAILURE, "snprintf");
return new_file;
}
static FILE * store_open_new(char *file) {
FILE *fp;
umask(0077);
fp = fopen(file, "w");
if (fp == NULL)
err(EXIT_FAILURE, "fopen %s", file);
return fp;
}
/*
* A little note on shell quoting:
* ' at beginning and end do most of the job for us, except when we have a '
* inside the quoted value. It can't be escaped directly, so we end the quote
* (with a ') and then add an escaped '. Possible ways are \' and "'" (in this
* case, the latter is used). Afterwards another normal ' is added and the
* quoted string continues.
*/
static inline void print_escaped(char *name, char *content) {
unsigned int i;
printf("export %s='", name);
for (i = 0; i < strlen(content); i++) {
if (content[i] == '\'')
fputs("'\"'\"'", stdout);
else
putchar(content[i]);
}
fputs("'\n", stdout);
}
static void command_disp(char *file, int command) {
char vname[PARAM_LENGTH];
char vcontent[VALUE_LENGTH];
FILE *fp = store_open(file);
if (fp == NULL)
exit(EXIT_SUCCESS);
while (fscanf(fp, SCAN_FORMAT, vname, vcontent) != EOF) {
if (command == CMD_LIST)
printf("%-15s = %s", vname, vcontent);
else
print_escaped(vname, vcontent);
}
if (fclose(fp) != 0)
err(EXIT_FAILURE, "fclose %s", file);
}
static void command_rm_save(char *old_file, char *param, char *value, int argc, int mode) {
char curparam[PARAM_LENGTH];
char curvalue[VALUE_LENGTH];
char *newvalue;
char *new_file = new_filename(old_file);
FILE *old_fp = store_open(old_file);
FILE *new_fp = store_open_new(new_file);
if (old_fp != NULL) {
while (fscanf(old_fp, SCAN_FORMAT, curparam, curvalue) != EOF) {
if (strcmp(curparam, param) != 0)
if (fprintf(new_fp, "%s %s\n", curparam, curvalue) <= 0)
err(EXIT_FAILURE, "fprintf %s", new_file);
}
if (fclose(old_fp) != 0)
err(EXIT_FAILURE, "fclose %s", old_file);
}
if (mode == CMD_SAVE) {
if (argc > 3)
newvalue = value;
else
newvalue = getenv(param);
if (newvalue == NULL)
errx(EXIT_FAILURE, "parameter '%s' has no value", param);
if ((strlen(param) > PARAM_LENGTH - 1) || (strlen(newvalue) > VALUE_LENGTH - 1))
errx(EXIT_FAILURE, "parameter or value too long (see man envstore -> LIMITATIONS)");
if (fprintf(new_fp, "%s %s\n", param, newvalue) <= 0)
err(EXIT_FAILURE, "fprintf %s", new_file);
}
if (fclose(new_fp) != 0)
err(EXIT_FAILURE, "fclose %s", new_file);
if (rename(new_file, old_file) != 0)
err(EXIT_FAILURE, "Unable to rename '%s' to '%s'", new_file, old_file);
}
static inline void command_clear(char *store_file) {
/*
* No error checking - assume that the file didn't exist in the first place
* if unlink fails.
*/
unlink(store_file);
}
int main(int argc, char **argv) {
char *store_file;
uid_t my_uid = geteuid();
if (argc < 2)
errx(EXIT_FAILURE, "Insufficient arguments");
store_file = getenv("ENVSTORE_FILE");
if (store_file == NULL) {
store_file = malloc(64);
if (store_file == NULL) {
err(EXIT_FAILURE, "malloc");
}
if (snprintf(store_file, 63, "/tmp/envstore-%d", (int)my_uid) < 10) {
err(EXIT_FAILURE, "snprintf");
}
}
switch (argv[1][0]) {
case 'c':
command_clear(store_file);
break;
case 'e':
command_disp(store_file, CMD_EVAL);
break;
case 'l':
command_disp(store_file, CMD_LIST);
break;
case 'r':
if (argc < 3)
errx(EXIT_FAILURE, "Usage: rm <parameter>");
command_rm_save(store_file, argv[2], argv[3], argc, CMD_RM);
break;
case 's':
if (argc < 3)
errx(EXIT_FAILURE, "Usage: save <parameter> [value]");
command_rm_save(store_file, argv[2], argv[3], argc, CMD_SAVE);
break;
default:
errx(EXIT_FAILURE, "Unknown action: %s", argv[1]);
break;
}
return EXIT_SUCCESS;
}
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