Commit a5ecbe62 authored by Wolfgang Denk's avatar Wolfgang Denk Committed by Tom Rini

Add SLRE - Super Light Regular Expression library

Downloaded from
and adapted for U-Boot environment.

Used to implement regex operations on environment variables.
Code size is ~ 3.5 KiB on PPC.

To enable this code, define the  CONFIG_REGEX  option in your board
config file.

Note:  There are more recent versions of the SLRE library available at ; unfortunately, the new code has a heavily
reorked API which makes it less usable for our purposes:
- the return code is strings, which are more difficult to process
- we don't get any information any more which sub-string of the data
  was matched by the given regex
- it is much more cumbersome to work with arbitrary expressions, where
  for example the number of substrings for capturing are not known at
  compile time
Also, there does not seem to be any real changes or improvements of
the functionality.

Because of this, we deliberately stick with the older code.

Note 2: the test code (built when SLRE_TEST is defined) was modified
to allow for more extensive testing; now we can test the regexp
matching on all lines on a text file (instead of the whole data in the
file as a single block).
Signed-off-by: default avatarWolfgang Denk <>
parent d87244d5
......@@ -930,6 +930,13 @@ The following options need to be configured:
XXX - this list needs to get updated!
- Regular expression support:
If this variable is defined, U-Boot is linked against
the SLRE (Super Light Regular Expression) library,
which adds regex support to some commands, as for
example "env grep" and "setexpr".
- Device tree:
If this variable is defined, U-Boot will use a device tree
* Copyright (c) 2004-2005 Sergey Lyubka <>
* All rights reserved
* "THE BEER-WARE LICENSE" (Revision 42):
* Sergey Lyubka wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return.
* Downloaded Sat Nov 5 17:42:08 CET 2011 at
* This is a regular expression library that implements a subset of Perl RE.
* Please refer to for detailed description.
* Usage example (parsing HTTP request):
* struct slre slre;
* struct cap captures[4 + 1]; // Number of braket pairs + 1
* ...
* slre_compile(&slre,"^(GET|POST) (\S+) HTTP/(\S+?)\r\n");
* if (slre_match(&slre, buf, len, captures)) {
* printf("Request line length: %d\n", captures[0].len);
* printf("Method: %.*s\n", captures[1].len, captures[1].ptr);
* printf("URI: %.*s\n", captures[2].len, captures[2].ptr);
* }
* Supported syntax:
* ^ Match beginning of a buffer
* $ Match end of a buffer
* () Grouping and substring capturing
* [...] Match any character from set
* [^...] Match any character but ones from set
* \s Match whitespace
* \S Match non-whitespace
* \d Match decimal digit
* \r Match carriage return
* \n Match newline
* + Match one or more times (greedy)
* +? Match one or more times (non-greedy)
* * Match zero or more times (greedy)
* *? Match zero or more times (non-greedy)
* ? Match zero or once
* \xDD Match byte with hex value 0xDD
* \meta Match one of the meta character: ^$().[*+?\
* Compiled regular expression
struct slre {
unsigned char code[256];
unsigned char data[256];
int code_size;
int data_size;
int num_caps; /* Number of bracket pairs */
int anchored; /* Must match from string start */
const char *err_str; /* Error string */
* Captured substring
struct cap {
const char *ptr; /* Pointer to the substring */
int len; /* Substring length */
* Compile regular expression. If success, 1 is returned.
* If error, 0 is returned and slre.err_str points to the error message.
int slre_compile(struct slre *, const char *re);
* Return 1 if match, 0 if no match.
* If `captured_substrings' array is not NULL, then it is filled with the
* values of captured substrings. captured_substrings[0] element is always
* a full matched substring. The round bracket captures start from
* captured_substrings[1].
* It is assumed that the size of captured_substrings array is enough to
* hold all captures. The caller function must make sure it is! So, the
* array_size = number_of_round_bracket_pairs + 1
int slre_match(const struct slre *, const char *buf, int buf_len,
struct cap *captured_substrings);
#ifdef SLRE_TEST
void slre_dump(const struct slre *r, FILE *fp);
#endif /* SLRE_TEST */
......@@ -72,6 +72,7 @@ COBJS-y += crc32.o
COBJS-y += ctype.o
COBJS-y += div64.o
COBJS-y += linux_string.o
COBJS-y += string.o
COBJS-y += time.o
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