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bionic: use the size of the file to determine property area size

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On the reader size, don't assume that the property size is PA_SIZE,
read it from the size of the file.  Allows init to use a different
property size without recompiling statically linked executables.

(cherry picked from commit 285b42a04cbe8e627a75c9bfb3c7cb3f7b539267)

Change-Id: I074204e9e6591b35faf7c1c58fb11ec162aff7bf
This commit is contained in:
Colin Cross 2013-06-24 18:42:21 -07:00
parent b116bf7628
commit 1ec20a086c
1 changed files with 14 additions and 8 deletions
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22
libc/bionic/system_properties.c
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@ -112,7 +112,8 @@ static char property_filename[PATH_MAX] = PROP_FILENAME;
prop_area *__system_property_area__ = NULL; prop_area *__system_property_area__ = NULL;
const size_t PA_DATA_SIZE = PA_SIZE - sizeof(prop_area); size_t pa_data_size;
size_t pa_size;
static int get_fd_from_env(void) static int get_fd_from_env(void)
{ {
@ -153,11 +154,14 @@ static int map_prop_area_rw()
if (ftruncate(fd, PA_SIZE) < 0) if (ftruncate(fd, PA_SIZE) < 0)
goto out; goto out;
pa = mmap(NULL, PA_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); pa_size = PA_SIZE;
pa_data_size = pa_size - sizeof(prop_area);
pa = mmap(NULL, pa_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if(pa == MAP_FAILED) if(pa == MAP_FAILED)
goto out; goto out;
memset(pa, 0, PA_SIZE); memset(pa, 0, pa_size);
pa->magic = PROP_AREA_MAGIC; pa->magic = PROP_AREA_MAGIC;
pa->version = PROP_AREA_VERSION; pa->version = PROP_AREA_VERSION;
/* reserve root node */ /* reserve root node */
@ -230,18 +234,20 @@ static int map_prop_area()
if ((fd_stat.st_uid != 0) if ((fd_stat.st_uid != 0)
|| (fd_stat.st_gid != 0) || (fd_stat.st_gid != 0)
|| ((fd_stat.st_mode & (S_IWGRP | S_IWOTH)) != 0) || ((fd_stat.st_mode & (S_IWGRP | S_IWOTH)) != 0)
|| (fd_stat.st_size < PA_SIZE) ) { || (fd_stat.st_size < sizeof(prop_area)) ) {
goto cleanup; goto cleanup;
} }
prop_area *pa = mmap(NULL, PA_SIZE, PROT_READ, MAP_SHARED, fd, 0); pa_size = fd_stat.st_size;
pa_data_size = pa_size - sizeof(prop_area);
prop_area *pa = mmap(NULL, pa_size, PROT_READ, MAP_SHARED, fd, 0);
if (pa == MAP_FAILED) { if (pa == MAP_FAILED) {
goto cleanup; goto cleanup;
} }
if((pa->magic != PROP_AREA_MAGIC) || (pa->version != PROP_AREA_VERSION)) { if((pa->magic != PROP_AREA_MAGIC) || (pa->version != PROP_AREA_VERSION)) {
munmap(pa, PA_SIZE); munmap(pa, pa_size);
goto cleanup; goto cleanup;
} }
@ -267,7 +273,7 @@ static void *new_prop_obj(size_t size, prop_off_t *off)
prop_area *pa = __system_property_area__; prop_area *pa = __system_property_area__;
size = ALIGN(size, sizeof(uint32_t)); size = ALIGN(size, sizeof(uint32_t));
if (pa->bytes_used + size > PA_DATA_SIZE) if (pa->bytes_used + size > pa_data_size)
return NULL; return NULL;
*off = pa->bytes_used; *off = pa->bytes_used;
@ -310,7 +316,7 @@ static prop_info *new_prop_info(const char *name, uint8_t namelen,
static void *to_prop_obj(prop_off_t off) static void *to_prop_obj(prop_off_t off)
{ {
if (off > PA_DATA_SIZE) if (off > pa_data_size)
return NULL; return NULL;
return __system_property_area__->data + off; return __system_property_area__->data + off;