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proc: deduplicate /proc/*/cmdline implementation 

Code can be sonsolidated if a dummy region of 0 length is used in normal
case of \0-separated command line:

1) [arg_start, arg_end) + [dummy len=0]
2) [arg_start, arg_end) + [env_start, env_end)

Link: http://lkml.kernel.org/r/20180221193335.GB28678@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan 2018-06-07 17:10:02 -07:00 committed by Linus Torvalds
parent 6a6cbe75db
commit 3cb4e162e4
1 changed files with 20 additions and 33 deletions
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53
fs/proc/base.c
View File

@ -213,9 +213,12 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
char *page;
unsigned long count = _count;
unsigned long arg_start, arg_end, env_start, env_end;
unsigned long len1, len2, len;
unsigned long p;
unsigned long len1, len2;
char __user *buf0 = buf;
struct {
unsigned long p;
unsigned long len;
} cmdline[2];
char c;
int rv;
@ -264,43 +267,21 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
if (access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_ANON) != 1)
goto end;
cmdline[0].p = arg_start;
cmdline[0].len = len1;
if (c == '\0') {
/* Command line (set of strings) occupies whole ARGV. */
if (len1 <= *pos)
goto end;
p = arg_start + *pos;
len = len1 - *pos;
while (count > 0 && len > 0) {
unsigned int nr_read;
nr_read = min3(count, len, PAGE_SIZE);
nr_read = access_remote_vm(mm, p, page, nr_read, FOLL_ANON);
if (nr_read == 0)
goto end;
if (copy_to_user(buf, page, nr_read)) {
rv = -EFAULT;
goto out_free_page;
}
p += nr_read;
len -= nr_read;
buf += nr_read;
count -= nr_read;
}
cmdline[1].len = 0;
} else {
/*
* Command line (1 string) occupies ARGV and
* extends into ENVP.
*/
struct {
unsigned long p;
unsigned long len;
} cmdline[2] = {
{ .p = arg_start, .len = len1 },
{ .p = env_start, .len = len2 },
};
cmdline[1].p = env_start;
cmdline[1].len = len2;
}
{
loff_t pos1 = *pos;
unsigned int i;
@ -310,6 +291,9 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
i++;
}
while (i < 2) {
unsigned long p;
unsigned long len;
p = cmdline[i].p + pos1;
len = cmdline[i].len - pos1;
while (count > 0 && len > 0) {
@ -324,7 +308,10 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
* Command line can be shorter than whole ARGV
* even if last "marker" byte says it is not.
*/
nr_write = strnlen(page, nr_read);
if (c == '\0')
nr_write = nr_read;
else
nr_write = strnlen(page, nr_read);
if (copy_to_user(buf, page, nr_write)) {
rv = -EFAULT;