proc: deduplicate /proc/*/cmdline implementation (3cb4e162) · Commits · 戴 / test

fs/proc/base.c

+20 −33

Original line number	Diff line number	Diff line
		@@ -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) {
		@@ -324,6 +308,9 @@ 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.
		*/
		if (c == '\0')
		nr_write = nr_read;
		else
		nr_write = strnlen(page, nr_read);

		if (copy_to_user(buf, page, nr_write)) {

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