kbuild: gen_init_cpio expands shell variables in file names (3b1ec9fb) · Commits · 戴 / test

Modify gen_init_cpio so that lines that specify files can contain what looks like a shell variable that's expanded during processing. For example: file /sbin/kinit ${RFS_BASE}/usr/src/klibc/kinit/kinit 0755 0 0 given RFS_BASE is "/some/directory" in the environment would be expanded to file /sbin/kinit /some/directory/usr/src/klibc/kinit/kinit 0755 0 0 If several environment variables appear in a line, they are all expanded with processing happening from left to right. Undefined variables expand to a null string. Syntax errors stop processing, letting the existing error handling show the user offending line. This patch helps embedded folks who frequently create several RFS directories and then switch between them as they're tuning an initramfs. Signed-off-by:

<gene.sally@timesys.com> Signed-off-by:

Sam Ravnborg <sam@ravnborg.org>

usr/gen_init_cpio.c

+27 −1

Original line number	Diff line number	Diff line
		@@ -370,6 +370,30 @@ error:
		return rc;
		}

		static char cpio_replace_env(char new_location)
		{
		char expanded[PATH_MAX + 1];
		char env_var[PATH_MAX + 1];
		char *start;
		char *end;

		for (start = NULL; (start = strstr(new_location, "${")); ) {
		end = strchr(start, '}');
		if (start < end) {
		env_var = expanded = '\0';
		strncat(env_var, start + 2, end - start - 2);
		strncat(expanded, new_location, start - new_location);
		strncat(expanded, getenv(env_var), PATH_MAX);
		strncat(expanded, end + 1, PATH_MAX);
		strncpy(new_location, expanded, PATH_MAX);
		} else
		break;
		}

		return new_location;
		}


		static int cpio_mkfile_line(const char *line)
		{
		char name[PATH_MAX + 1];
		@@ -415,7 +439,8 @@ static int cpio_mkfile_line(const char *line)
		} else {
		dname = name;
		}
		rc = cpio_mkfile(dname, location, mode, uid, gid, nlinks);
		rc = cpio_mkfile(dname, cpio_replace_env(location),
		mode, uid, gid, nlinks);
		fail:
		if (dname_len) free(dname);
		return rc;
		@@ -439,6 +464,7 @@ void usage(const char *prog)
		"\n"
		"<name> name of the file/dir/nod/etc in the archive\n"
		"<location> location of the file in the current filesystem\n"
		" expands shell variables quoted with ${}\n"
		"<target> link target\n"
		"<mode> mode/permissions of the file\n"
		"<uid> user id (0=root)\n"

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