path: root/src/common/util-common.c

/*
 *  util-common.c
 *
 *  Copyright (c) 2006-2021 Pacman Development Team <pacman-dev@archlinux.org>
 *
 *  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 2 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/>.
 */

#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "util-common.h"


/** Create a string representing bytes in hexadecimal.
 * @param bytes the bytes to represent in hexadecimal
 * @param size number of bytes to consider
 * @return a NULL terminated string with the hexadecimal representation of
 * bytes or NULL on error. This string must be freed.
 */
char *hex_representation(const unsigned char *bytes, size_t size)
{
	static const char *hex_digits = "0123456789abcdef";
	char *str = malloc(2 * size + 1);
	size_t i;

	if(!str) {
		return NULL;
	}

	for(i = 0; i < size; i++) {
		str[2 * i] = hex_digits[bytes[i] >> 4];
		str[2 * i + 1] = hex_digits[bytes[i] & 0x0f];
	}

	str[2 * size] = '\0';

	return str;
}

/** Parse the basename of a program from a path.
* @param path path to parse basename from
*
* @return everything following the final '/'
*/
const char *mbasename(const char *path)
{
	const char *last = strrchr(path, '/');
	if(last) {
		return last + 1;
	}
	return path;
}

/** Parse the dirname of a program from a path.
* The path returned should be freed.
* @param path path to parse dirname from
*
* @return everything preceding the final '/'
*/
char *mdirname(const char *path)
{
	char *ret, *last;

	/* null or empty path */
	if(path == NULL || *path == '\0') {
		return strdup(".");
	}

	if((ret = strdup(path)) == NULL) {
		return NULL;
	}

	last = strrchr(ret, '/');

	if(last != NULL) {
		/* we found a '/', so terminate our string */
		if(last == ret) {
			/* return "/" for root */
			last++;
		}
		*last = '\0';
		return ret;
	}

	/* no slash found */
	free(ret);
	return strdup(".");
}

/** lstat wrapper that treats /path/dirsymlink/ the same as /path/dirsymlink.
 * Linux lstat follows POSIX semantics and still performs a dereference on
 * the first, and for uses of lstat in libalpm this is not what we want.
 * @param path path to file to lstat
 * @param buf structure to fill with stat information
 * @return the return code from lstat
 */
int llstat(char *path, struct stat *buf)
{
	int ret;
	char *c = NULL;
	size_t len = strlen(path);

	while(len > 1 && path[len - 1] == '/') {
		--len;
		c = path + len;
	}

	if(c) {
		*c = '\0';
		ret = lstat(path, buf);
		*c = '/';
	} else {
		ret = lstat(path, buf);
	}

	return ret;
}

/** Wrapper around fgets() which properly handles EINTR
 * @param s string to read into
 * @param size maximum length to read
 * @param stream stream to read from
 * @return value returned by fgets()
 */
char *safe_fgets(char *s, int size, FILE *stream)
{
	char *ret;
	int errno_save = errno, ferror_save = ferror(stream);
	while((ret = fgets(s, size, stream)) == NULL && !feof(stream)) {
		if(errno == EINTR) {
			/* clear any errors we set and try again */
			errno = errno_save;
			if(!ferror_save) {
				clearerr(stream);
			}
		} else {
			break;
		}
	}
	return ret;
}

/* Trim whitespace and newlines from a string
 */
size_t strtrim(char *str)
{
	char *end, *pch = str;

	if(str == NULL || *str == '\0') {
		/* string is empty, so we're done. */
		return 0;
	}

	while(isspace((unsigned char)*pch)) {
		pch++;
	}
	if(pch != str) {
		size_t len = strlen(pch);
		/* check if there wasn't anything but whitespace in the string. */
		if(len == 0) {
			*str = '\0';
			return 0;
		}
		memmove(str, pch, len + 1);
		pch = str;
	}

	end = (str + strlen(str) - 1);
	while(isspace((unsigned char)*end)) {
		end--;
	}
	*++end = '\0';

	return end - pch;
}

#ifndef HAVE_STRNLEN
/* A quick and dirty implementation derived from glibc */
/** Determines the length of a fixed-size string.
 * @param s string to be measured
 * @param max maximum number of characters to search for the string end
 * @return length of s or max, whichever is smaller
 */
static size_t strnlen(const char *s, size_t max)
{
	register const char *p;
	for(p = s; *p && max--; ++p);
	return (p - s);
}
#endif

#ifndef HAVE_STRNDUP
/** Copies a string.
 * Returned string needs to be freed
 * @param s string to be copied
 * @param n maximum number of characters to copy
 * @return pointer to the new string on success, NULL on error
 */
char *strndup(const char *s, size_t n)
{
	size_t len = strnlen(s, n);
	char *new = (char *) malloc(len + 1);

	if(new == NULL) {
		return NULL;
	}

	new[len] = '\0';
	return (char *)memcpy(new, s, len);
}
#endif

void wordsplit_free(char **ws)
{
	if(ws) {
		char **c;
		for(c = ws; *c; c++) {
			free(*c);
		}
		free(ws);
	}
}

char **wordsplit(const char *str)
{
	const char *c = str, *end;
	char **out = NULL, **outsave;
	size_t count = 0;

	if(str == NULL) {
		errno = EINVAL;
		return NULL;
	}

	for(c = str; isspace(*c); c++);
	while(*c) {
		size_t wordlen = 0;

		/* extend our array */
		outsave = out;
		if((out = realloc(out, (count + 1) * sizeof(char*))) == NULL) {
			out = outsave;
			goto error;
		}

		/* calculate word length and check for unbalanced quotes */
		for(end = c; *end && !isspace(*end); end++) {
			if(*end == '\'' || *end == '"') {
				char quote = *end;
				while(*(++end) && *end != quote) {
					if(*end == '\\' && *(end + 1) == quote) {
						end++;
					}
					wordlen++;
				}
				if(*end != quote) {
					errno = EINVAL;
					goto error;
				}
			} else {
				if(*end == '\\' && (end[1] == '\'' || end[1] == '"')) {
					end++; /* skip the '\\' */
				}
				wordlen++;
			}
		}

		if(wordlen == (size_t) (end - c)) {
			/* no internal quotes or escapes, copy it the easy way */
			if((out[count++] = strndup(c, wordlen)) == NULL) {
				goto error;
			}
		} else {
			/* manually copy to remove quotes and escapes */
			char *dest = out[count++] = malloc(wordlen + 1);
			if(dest == NULL) { goto error; }
			while(c < end) {
				if(*c == '\'' || *c == '"') {
					char quote = *c;
					/* we know there must be a matching end quote,
					 * no need to check for '\0' */
					for(c++; *c != quote; c++) {
						if(*c == '\\' && *(c + 1) == quote) {
							c++;
						}
						*(dest++) = *c;
					}
					c++;
				} else {
					if(*c == '\\' && (c[1] == '\'' || c[1] == '"')) {
						c++; /* skip the '\\' */
					}
					*(dest++) = *(c++);
				}
			}
			*dest = '\0';
		}

		if(*end == '\0') {
			break;
		} else {
			for(c = end + 1; isspace(*c); c++);
		}
	}

	outsave = out;
	if((out = realloc(out, (count + 1) * sizeof(char*))) == NULL) {
		out = outsave;
		goto error;
	}

	out[count++] = NULL;

	return out;

error:
	/* can't use wordsplit_free here because NULL has not been appended */
	while(count) {
		free(out[--count]);
	}
	free(out);
	return NULL;
}