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/*
* music player command (mpc)
* Copyright 2003-2019 The Music Player Daemon Project
* http://www.musicpd.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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "format.h"
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/**
* Reallocate the given string and append the source string.
*/
gcc_malloc
static char *
string_append(char *dest, const char *src, size_t len)
{
size_t destlen = dest != NULL
? strlen(dest)
: 0;
dest = realloc(dest, destlen + len + 1);
memcpy(dest + destlen, src, len);
dest[destlen + len] = '\0';
return dest;
}
/**
* Skip the format string until the current group is closed by either
* '&', '|' or ']' (supports nesting).
*/
gcc_pure
static const char *
skip_format(const char *p)
{
unsigned stack = 0;
while (*p != '\0') {
if (*p == '[')
stack++;
else if (*p == '#' && p[1] != '\0')
/* skip escaped stuff */
++p;
else if (stack > 0) {
if (*p == ']')
--stack;
} else if (*p == '&' || *p == '|' || *p == ']')
break;
++p;
}
return p;
}
static bool
is_name_char(char ch)
{
return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') ||
(ch >= '0' && ch <= '9') || ch == '_';
}
static char *
format_object2(const char *format, const char **last, const void *object,
const char *(*getter)(const void *object, const char *name))
{
char *ret = NULL;
const char *p;
bool found = false;
for (p = format; *p != '\0';) {
switch (p[0]) {
case '|':
++p;
if (!found) {
/* nothing found yet: try the next
section */
free(ret);
ret = NULL;
} else
/* already found a value: skip the
next section */
p = skip_format(p);
break;
case '&':
++p;
if (!found)
/* nothing found yet, so skip this
section */
p = skip_format(p);
else
/* we found something yet, but it will
only be used if the next section
also found something, so reset the
flag */
found = false;
break;
case '[': {
char *t = format_object2(p + 1, &p, object, getter);
if (t != NULL) {
ret = string_append(ret, t, strlen(t));
free(t);
found = true;
}
}
break;
case ']':
if (last != NULL)
*last = p + 1;
if (!found) {
free(ret);
ret = NULL;
}
return ret;
case '\\': {
/* take care of escape sequences */
char ltemp;
switch (p[1]) {
case 'a':
ltemp = '\a';
break;
case 'b':
ltemp = '\b';
break;
case 't':
ltemp = '\t';
break;
case 'n':
ltemp = '\n';
break;
case 'v':
ltemp = '\v';
break;
case 'f':
ltemp = '\f';
break;
case 'r':
ltemp = '\r';
break;
case '[':
case ']':
ltemp = p[1];
break;
default:
/* unknown escape: copy the
backslash */
ltemp = p[0];
--p;
break;
}
ret = string_append(ret, <emp, 1);
p += 2;
}
break;
case '%': {
/* find the extent of this format specifier
(stop at \0, ' ', or esc) */
const char *end = p + 1;
while (is_name_char(*end))
++end;
const size_t length = end - p + 1;
if (*end != '%') {
ret = string_append(ret, p, length - 1);
p = end;
continue;
}
char name[32];
if (length > (int)sizeof(name)) {
ret = string_append(ret, p, length);
p = end + 1;
continue;
}
memcpy(name, p + 1, length - 2);
name[length - 2] = 0;
const char *value = getter(object, name);
size_t value_length;
if (value != NULL) {
if (*value != 0)
found = true;
value_length = strlen(value);
} else {
/* unknown variable: copy verbatim
from format string */
value = p;
value_length = length;
}
ret = string_append(ret, value, value_length);
/* advance past the specifier */
p = end + 1;
}
break;
case '#':
/* let the escape character escape itself */
if (p[1] != '\0') {
ret = string_append(ret, p + 1, 1);
p += 2;
break;
}
/* fall through */
default:
/* pass-through non-escaped portions of the format string */
ret = string_append(ret, p, 1);
++p;
}
}
if (last != NULL)
*last = p;
return ret;
}
char *
format_object(const char *format, const void *object,
const char *(*getter)(const void *object, const char *name))
{
return format_object2(format, NULL, object, getter);
}
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