/* Read the environment variable of current process specified by @key. */
int cfs_get_environ(const char *key, char *value, int *val_len)
{
struct mm_struct *mm;
char *buffer;
int buf_len = PAGE_CACHE_SIZE;
int key_len = strlen(key);
unsigned long addr;
int rc;
bool skip = false;
ENTRY;
buffer = kmalloc(buf_len, GFP_USER);
if (!buffer)
RETURN(-ENOMEM);
mm = get_task_mm(current);
if (!mm) {
kfree(buffer);
RETURN(-EINVAL);
}
addr = mm->env_start;
while (addr < mm->env_end) {
int this_len, retval, scan_len;
char *env_start, *env_end;
memset(buffer, 0, buf_len);
this_len = min_t(int, mm->env_end - addr, buf_len);
retval = cfs_access_process_vm(current, mm, addr, buffer,
this_len, 0);
if (retval < 0)
GOTO(out, rc = retval);
else if (retval != this_len)
break;
addr += retval;
/* Parse the buffer to find out the specified key/value pair.
* The "key=value" entries are separated by '\0'. */
env_start = buffer;
scan_len = this_len;
while (scan_len) {
char *entry;
int entry_len;
env_end = memscan(env_start, '\0', scan_len);
LASSERT(env_end >= env_start &&
env_end <= env_start + scan_len);
/* The last entry of this buffer cross the buffer
* boundary, reread it in next cycle. */
if (unlikely(env_end - env_start == scan_len)) {
/* Just skip the entry larger than page size,
* it can't be jobID env variable. */
if (unlikely(scan_len == this_len))
skip = true;
else
addr -= scan_len;
break;
} else if (unlikely(skip)) {
skip = false;
goto skip;
}
entry = env_start;
entry_len = env_end - env_start;
/* Key length + length of '=' */
if (entry_len > key_len + 1 &&
!memcmp(entry, key, key_len)) {
entry += key_len + 1;
entry_len -= key_len + 1;
/* The 'value' buffer passed in is too small.*/
if (entry_len >= *val_len)
GOTO(out, rc = -EOVERFLOW);
memcpy(value, entry, entry_len);
*val_len = entry_len;
GOTO(out, rc = 0);
}
skip:
scan_len -= (env_end - env_start + 1);
env_start = env_end + 1;
}
}
GOTO(out, rc = -ENOENT);
out:
mmput(mm);
kfree((void *)buffer);
return rc;
}
/* Read the environment variable of current process specified by @key. */
int cfs_get_environ(const char *key, char *value, int *val_len)
{
struct mm_struct *mm;
char *buffer;
int buf_len = PAGE_CACHE_SIZE;
int key_len = strlen(key);
unsigned long addr;
int rc;
ENTRY;
buffer = kmalloc(buf_len, GFP_USER);
if (!buffer)
RETURN(-ENOMEM);
mm = get_task_mm(current);
if (!mm) {
kfree(buffer);
RETURN(-EINVAL);
}
/* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
* which is already holding mmap_sem for writes. If some other
* thread gets the write lock in the meantime, this thread will
* block, but at least it won't deadlock on itself. LU-1735 */
if (down_read_trylock(&mm->mmap_sem) == 0) {
kfree(buffer);
return -EDEADLK;
}
up_read(&mm->mmap_sem);
addr = mm->env_start;
while (addr < mm->env_end) {
int this_len, retval, scan_len;
char *env_start, *env_end;
memset(buffer, 0, buf_len);
this_len = min_t(int, mm->env_end - addr, buf_len);
retval = cfs_access_process_vm(current, addr, buffer,
this_len, 0);
if (retval != this_len)
break;
addr += retval;
/* Parse the buffer to find out the specified key/value pair.
* The "key=value" entries are separated by '\0'. */
env_start = buffer;
scan_len = this_len;
while (scan_len) {
char *entry;
int entry_len;
env_end = memscan(env_start, '\0', scan_len);
LASSERT(env_end >= env_start &&
env_end <= env_start + scan_len);
/* The last entry of this buffer cross the buffer
* boundary, reread it in next cycle. */
if (unlikely(env_end - env_start == scan_len)) {
/* This entry is too large to fit in buffer */
if (unlikely(scan_len == this_len)) {
CERROR("Too long env variable.\n");
GOTO(out, rc = -EINVAL);
}
addr -= scan_len;
break;
}
entry = env_start;
entry_len = env_end - env_start;
/* Key length + length of '=' */
if (entry_len > key_len + 1 &&
!memcmp(entry, key, key_len)) {
entry += key_len + 1;
entry_len -= key_len + 1;
/* The 'value' buffer passed in is too small.*/
if (entry_len >= *val_len)
GOTO(out, rc = -EOVERFLOW);
memcpy(value, entry, entry_len);
*val_len = entry_len;
GOTO(out, rc = 0);
}
scan_len -= (env_end - env_start + 1);
env_start = env_end + 1;
}
}
GOTO(out, rc = -ENOENT);
out:
mmput(mm);
kfree((void *)buffer);
return rc;
}
