99 lines
3 KiB
C
99 lines
3 KiB
C
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#define _GNU_SOURCE
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#include <stdarg.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <time.h>
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#include "sh.h"
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char * vars[NUM_VARS];
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const char * var_names[NUM_VARS] = {
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"LOWERDIR",
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"UPPERDIR",
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"MOUNTDIR",
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"LOWERNEW",
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"UPPERNEW",
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};
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int quote(const char *filename, FILE *output);
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FILE* create_shell_script(char *tmp_path_buffer) {
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int tmp_file = mkstemps(tmp_path_buffer, 3); // the 3 is for suffix length (".sh")
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if (tmp_file < 0) { return NULL; }
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fchmod(tmp_file, S_IRWXU); // chmod to 0700
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FILE* f = fdopen(tmp_file, "w");
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if (f == NULL) { return NULL; }
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fprintf(f, "#!/usr/bin/env bash\n");
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fprintf(f, "set -x\n");
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time_t rawtime;
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time (&rawtime);
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fprintf(f, "# This shell script is generated by overlayfs-tools on %s\n", ctime (&rawtime));
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for (int i=0; i < NUM_VARS; i++) {
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if (vars[i]) {
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fprintf(f, "%s=", var_names[i]);
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if (quote(vars[i], f) < 0) { return NULL; }
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if (fputc('\n', f) == EOF) { return NULL; }
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}
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}
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// Non-empty *NEW vars make a backup copy and override *DIR vars
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if (vars[LOWERNEW]) {
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fprintf(f, "rm -rf \"$LOWERNEW\"\n");
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fprintf(f, "cp -a \"$LOWERDIR\" \"$LOWERNEW\"\n");
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fprintf(f, "LOWERDIR=");
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if (quote(vars[LOWERNEW], f) < 0) { return NULL; }
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if (fputc('\n', f) == EOF) { return NULL; }
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}
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if (vars[UPPERNEW]) {
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fprintf(f, "rm -rf \"$UPPERNEW\"\n");
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fprintf(f, "cp -a \"$UPPERDIR\" \"$UPPERNEW\"\n");
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fprintf(f, "UPPERDIR=");
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if (quote(vars[UPPERNEW], f) < 0) { return NULL; }
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if (fputc('\n', f) == EOF) { return NULL; }
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}
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return f;
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}
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int quote(const char *filename, FILE *output) {
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if (fputc('\'', output) == EOF) { return -1; }
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for (const char *s = filename; *s != '\0'; s++) {
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if (*s == '\'') {
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if (fprintf(output, "'\"'\"'") < 0) { return -1; }
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} else {
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if (fputc(*s, output) == EOF) { return -1; }
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}
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}
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if (fputc('\'', output) == EOF) { return -1; }
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return 0;
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}
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int substitue(char what, const char *filename, FILE *output) {
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int i;
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for (i=0; i < NUM_VARS; i++)
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if (vars[i] && var_names[i][0] == what)
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break;
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if (i == NUM_VARS) { return -1; }
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// filename prefix must match the var value
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int prefix = strlen(vars[i]);
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if (strncmp(filename, vars[i], prefix)) { return -1; }
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filename += prefix;
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fprintf(output, "\"$%s\"", var_names[i]);
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return quote(filename, output);
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}
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int command(FILE *output, const char *command_format, ...) {
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va_list arg;
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va_start(arg, command_format);
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for (size_t i = 0; command_format[i] != '\0'; i++) {
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if (command_format[i] == '%') {
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const char *s = va_arg(arg, char *);
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if (substitue(command_format[++i], s, output) < 0) { return -1; }
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} else {
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if (fputc(command_format[i], output) == EOF) { return -1; }
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}
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}
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va_end(arg);
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if (fputc('\n', output) == EOF) { return -1; }
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return 0;
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}
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