Tools to make secret sharing easier.
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/*
* gfsec - Secret sharing tools
* Copyright (C) 2016 Damien Goutte-Gattat
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "util.h"
#include <string.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <xmem.h>
/**
* Checks if the specified file exists.
*
* @param path The filename to check.
*
* @return 0 if the file exists, or -1 (check errno for details).
*/
int
file_exists(const char *path)
{
struct stat st;
assert(path != NULL);
return stat(path, &st);
}
/**
* Gets the size of the specified file.
*
* @param f The file object.
*
* @return The file's size, or -1 if an error occured
* (check errno for details).
*/
long
get_file_size(FILE *f)
{
long s;
assert(f != NULL);
if ( fseek(f, 0, SEEK_END) == -1
|| (s = ftell(f)) == -1
|| fseek(f, 0, SEEK_SET) == -1 )
s = -1;
return s;
}
/**
* Reads a file into memory.
*
* @param filename The path to the file to read.
* @param len The address where the file's size will be stored
* (may be NULL).
* @param max Do not read the file if its size exceeds this value;
* if zero, always read the file no matter its size.
*
* @return A newly allocated buffer containing the file's data, or
* NULL if an error occured (check errno for details).
*/
unsigned char *
read_file(const char *filename, size_t *len, size_t max)
{
FILE *f;
unsigned char *blob = NULL;
assert(filename != NULL);
if ( (f = fopen(filename, "r")) ) {
long size;
size_t nread;
if ( (size = get_file_size(f)) != -1 ) {
if ( max != 0 && (unsigned long) size > max )
errno = EFBIG;
else {
blob = xmalloc(size);
if ( (nread = fread(blob, 1, size, f)) < (unsigned long) size ) {
free(blob);
blob = NULL;
}
else if ( len )
*len = nread;
}
}
fclose(f);
}
return blob;
}
/**
* Writes a buffer into a file.
*
* @param filename The path to the file to write.
* @param contents The buffer to write.
* @param len The size of the \c contents buffer.
*
* @return The number of bytes written, or -1 if an error occured
* (check errno for details).
*/
int
write_file(const char *filename, const unsigned char *contents, size_t len)
{
FILE *f;
int rc;
assert(filename != NULL);
assert(contents != NULL);
if ( (f = fopen(filename, "w")) ) {
rc = fwrite(contents, sizeof(char), len, f) == len ? 0 : -1;
fclose(f);
}
return rc;
}
/**
* Gets the basename part of a path.
*
* @param path The path to extract the basename from.
*
* @return A newly allocated buffer containing the basename.
*/
char *
get_file_basename(const char *path)
{
char *last_slash, *last_dot;
unsigned n;
assert(path != NULL);
if ( (last_slash = strrchr(path, '/')) )
path = last_slash + 1;
if ( (last_dot = strrchr(path, '.')) )
n = last_dot - path;
else
n = strlen(path);
return xstrndup(path, n);
}