Magisk/jni/resetprop/resetprop.cpp

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2017-02-28 09:52:27 +01:00
/*
*
* resetprop.cpp
*
* Copyright 2016 nkk71 <nkk71x@gmail.com>
* Copyright 2016 topjohnwu <topjohnwu#gmail.com>
*
*
* 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 <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include "_system_properties.h"
#include <sys/system_properties.h>
/* Info:
*
* all changes are in
*
* bionic/libc/bionic/system_properties.cpp
*
* Functions that need to be patched/added in system_properties.cpp
*
* int __system_properties_init()
* on android 7, first tear down the everything then let it initialize again:
* if (initialized) {
* //list_foreach(contexts, [](context_node* l) { l->reset_access(); });
* //return 0;
* free_and_unmap_contexts();
* initialized = false;
* }
*
*
* static prop_area* map_prop_area(const char* filename, bool is_legacy)
* we dont want this read only so change: 'O_RDONLY' to 'O_RDWR'
*
* static prop_area* map_fd_ro(const int fd)
* we dont want this read only so change: 'PROT_READ' to 'PROT_READ | PROT_WRITE'
*
*
* Copy the code of prop_info *prop_area::find_property, and modify to delete props
* const prop_info *prop_area::find_property_and_del(prop_bt *const trie, const char *name)
* {
* ...
* ... Do not alloc a new prop_bt here, remove all code involve alloc_if_needed
* ...
*
* if (prop_offset != 0) {
* atomic_store_explicit(&current->prop, 0, memory_order_release); // Add this line to nullify the prop entry
* return to_prop_info(&current->prop);
* } else {
*
* ....
* }
*
*
* by patching just those functions directly, all other functions should be ok
* as is.
*
*
*/
int verbose = 0, del = 0, file = 0, trigger = 1;
static bool is_legal_property_name(const char* name, size_t namelen)
{
size_t i;
if (namelen >= PROP_NAME_MAX) return false;
if (namelen < 1) return false;
if (name[0] == '.') return false;
if (name[namelen - 1] == '.') return false;
/* Only allow alphanumeric, plus '.', '-', or '_' */
/* Don't allow ".." to appear in a property name */
for (i = 0; i < namelen; i++) {
if (name[i] == '.') {
// i=0 is guaranteed to never have a dot. See above.
if (name[i-1] == '.') return false;
continue;
}
if (name[i] == '_' || name[i] == '-') continue;
if (name[i] >= 'a' && name[i] <= 'z') continue;
if (name[i] >= 'A' && name[i] <= 'Z') continue;
if (name[i] >= '0' && name[i] <= '9') continue;
return false;
}
return true;
}
int x_property_set(const char *name, const char *value)
{
int ret;
char value_read[PROP_VALUE_MAX];
size_t namelen = strlen(name);
size_t valuelen = strlen(value);
if (trigger) {
printf("Set with property_service: '%s'='%s'\n", name, value);
} else {
printf("Modify data structure: '%s'='%s'\n", name, value);
}
__system_property_get(name, value_read);
if(strlen(value_read)) {
printf("Existing property: '%s'='%s'\n", name, value_read);
if (trigger) {
if (!strncmp(name, "ro.", 3)) __system_property_del(name); // Only delete ro props
ret = __system_property_set(name, value);
} else {
ret = __system_property_update((prop_info*) __system_property_find(name), value, valuelen);
}
} else {
if (trigger) {
ret = __system_property_set(name, value);
} else {
ret = __system_property_add(name, namelen, value, valuelen);
}
}
if (ret != 0) {
fprintf(stderr, "Failed to set '%s'='%s'\n", name, value);
return ret;
}
__system_property_get(name, value_read);
printf("Recheck property: '%s'='%s'\n", name, value_read);
return 0;
}
int read_prop_file(const char* filename) {
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printf("Attempting to read props from \'%s\'\n", filename);
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FILE *fp = fopen(filename, "r");
if (fp == NULL) {
fprintf(stderr, "Cannot open \'%s\'\n", filename);
return 1;
}
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char *line = NULL, *pch;
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size_t len;
ssize_t read;
int comment = 0, i;
while ((read = getline(&line, &len, fp)) != -1) {
// Remove the trailing newline
if (line[read - 1] == '\n') {
line[read - 1] = '\0';
--read;
}
comment = 0;
for (i = 0; i < read; ++i) {
// Ignore starting spaces
if (line[i] == ' ') continue;
else {
// A line starting with # is ignored
if (line[i] == '#') comment = 1;
break;
}
}
if (comment) continue;
pch = strchr(line, '=');
// Ignore ivalid formats
if ( ((pch == NULL) || (i >= (pch - line))) || (pch >= line + read - 1) ) continue;
// Separate the string
*pch = '\0';
x_property_set(line + i, pch + 1);
}
free(line);
fclose(fp);
return 0;
}
int usage(char* name) {
fprintf(stderr, "usage: %s [-v] [-n] [--file propfile] [--delete name] [ name value ] \n", name);
fprintf(stderr, " -v :\n");
fprintf(stderr, " verbose output (Default: Disabled)\n");
fprintf(stderr, " -n :\n");
fprintf(stderr, " no event triggers when changing props (Default: Will trigger events)\n");
fprintf(stderr, " --file propfile :\n");
fprintf(stderr, " Read props from prop files (e.g. build.prop)\n");
fprintf(stderr, " --delete name :\n");
fprintf(stderr, " Remove a prop entry\n\n");
return 1;
}
int main(int argc, char *argv[])
{
int exp_arg = 2, stdout_bak, null;
char *name, *value, *filename;
if (argc < 3) {
return usage(argv[0]);
}
for (int i = 1; i < argc; ++i) {
if (!strcmp("-v", argv[i])) {
verbose = 1;
} else if (!strcmp("-n", argv[i])) {
trigger = 0;
} else if (!strcmp("--file", argv[i])) {
file = 1;
exp_arg = 1;
} else if (!strcmp("--delete", argv[i])) {
del = 1;
exp_arg = 1;
} else {
if (i + exp_arg > argc) {
return usage(argv[0]);
}
if (file) {
filename = argv[i];
break;
} else {
if(!is_legal_property_name(argv[i], strlen(argv[i]))) {
fprintf(stderr, "Illegal property name \'%s\'\n", argv[i]);
return 1;
}
name = argv[i];
if (exp_arg > 1) {
if (strlen(argv[i + 1]) >= PROP_VALUE_MAX) {
fprintf(stderr, "Value too long \'%s\'\n", argv[i + 1]);
return 1;
}
value = argv[i + 1];
}
break;
}
}
}
if (!verbose) {
fflush(stdout);
stdout_bak = dup(1);
null = open("/dev/null", O_WRONLY);
dup2(null, 1);
}
printf("resetprop by nkk71 & topjohnwu\n");
printf("Initializing...\n");
if (__system_properties_init()) {
fprintf(stderr, "Error during init\n");
return 1;
}
if (file) {
if (read_prop_file(filename)) return 1;
} else if (del) {
printf("Attempting to delete '%s'\n", name);
if (__system_property_del(name)) return 1;
} else {
if(x_property_set(name, value)) return 1;
}
printf("Done!\n\n");
return 0;
}