setexpr: add regex substring matching and substitution
Add "setexpr name gsub r s [t]" and "setexpr name sub r s [t]" commands which implement substring matching for the regular expression <r> in the string <t>, and substitution of the string <s>. The result is assigned to the environment variable <name>. If <t> is not supplied, the previous value of <name> is used instead. "gsub" performs global substitution, while "sub" will replace only the first substring. Both commands are closely modeled after the gawk functions with the same names. Examples: - Generate broadcast address by substituting the last two numbers of the IP address by "255.255": => print ipaddr ipaddr=192.168.1.104 => setexpr broadcast sub "(.*\\.).*\\..*" "\\1255.255" $ipaddr broadcast=192.168.255.255 - Depending on keyboard configuration (German vs. US keyboard) a barcode scanner may initialize the MAC address as C0:E5:4E:02:06:DC or as C0>E5>4E>02>06>DC. Make sure we always have a correct value: => print ethaddr ethaddr=C0>E5>4E>02>06>DC => setexpr ethaddr gsub > : ethaddr=C0:E5:4E:02:06:DC - Do the same, but substitute one step at a time in a loop until no futher matches: => setenv ethaddr C0>E5>4E>02>06>DC => while setexpr ethaddr sub > : > do > echo ----- > done ethaddr=C0:E5>4E>02>06>DC ----- ethaddr=C0:E5:4E>02>06>DC ----- ethaddr=C0:E5:4E:02>06>DC ----- ethaddr=C0:E5:4E:02:06>DC ----- ethaddr=C0:E5:4E:02:06:DC ----- C0:E5:4E:02:06:DC: No match => print ethaddr ethaddr=C0:E5:4E:02:06:DC etc. To enable this feature, the CONFIG_REGEX option has to be defined in the board config file. Signed-off-by: Wolfgang Denk <wd@denx.de>
This commit is contained in:
Wolfgang Denk
Tom Rini
parent
103c94b104
commit
855f18ea0e
@ -1,5 +1,6 @@
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/*
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* Copyright 2008 Freescale Semiconductor, Inc.
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* Copyright 2013 Wolfgang Denk <wd@denx.de>
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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@ -50,13 +51,263 @@ static ulong get_arg(char *s, int w)
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}
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}
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#ifdef CONFIG_REGEX
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#include <slre.h>
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#define SLRE_BUFSZ 16384
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#define SLRE_PATSZ 4096
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/*
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* memstr - Find the first substring in memory
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* @s1: The string to be searched
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* @s2: The string to search for
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*
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* Similar to and based on strstr(),
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* but strings do not need to be NUL terminated.
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*/
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static char *memstr(const char *s1, int l1, const char *s2, int l2)
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{
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if (!l2)
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return (char *)s1;
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while (l1 >= l2) {
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l1--;
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if (!memcmp(s1, s2, l2))
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return (char *)s1;
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s1++;
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}
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return NULL;
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}
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static char *substitute(char *string, /* string buffer */
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int *slen, /* current string length */
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int ssize, /* string bufer size */
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const char *old,/* old (replaced) string */
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int olen, /* length of old string */
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const char *new,/* new (replacement) string */
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int nlen) /* length of new string */
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{
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char *p = memstr(string, *slen, old, olen);
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if (p == NULL)
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return NULL;
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debug("## Match at pos %ld: match len %d, subst len %d\n",
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(long)(p - string), olen, nlen);
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/* make sure replacement matches */
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if (*slen + nlen - olen > ssize) {
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printf("## error: substitution buffer overflow\n");
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return NULL;
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}
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/* move tail if needed */
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if (olen != nlen) {
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int tail, len;
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len = (olen > nlen) ? olen : nlen;
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tail = ssize - (p + len - string);
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debug("## tail len %d\n", tail);
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memmove(p + nlen, p + olen, tail);
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}
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/* insert substitue */
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memcpy(p, new, nlen);
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*slen += nlen - olen;
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return p + nlen;
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}
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/*
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* Perform regex operations on a environment variable
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*
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* Returns 0 if OK, 1 in case of errors.
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*/
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static int regex_sub(const char *name,
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const char *r, const char *s, const char *t,
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int global)
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{
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struct slre slre;
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char data[SLRE_BUFSZ];
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char *datap = data;
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const char *value;
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int res, len, nlen, loop;
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if (name == NULL)
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return 1;
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if (slre_compile(&slre, r) == 0) {
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printf("Error compiling regex: %s\n", slre.err_str);
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return 1;
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}
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if (t == NULL) {
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value = getenv(name);
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if (value == NULL) {
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printf("## Error: variable \"%s\" not defined\n", name);
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return 1;
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}
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t = value;
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}
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debug("REGEX on %s=%s\n", name, t);
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debug("REGEX=\"%s\", SUBST=\"%s\", GLOBAL=%d\n",
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r, s ? s : "<NULL>", global);
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len = strlen(t);
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if (len + 1 > SLRE_BUFSZ) {
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printf("## error: subst buffer overflow: have %d, need %d\n",
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SLRE_BUFSZ, len + 1);
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return 1;
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}
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strcpy(data, t);
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if (s == NULL)
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nlen = 0;
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else
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nlen = strlen(s);
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for (loop = 0;; loop++) {
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struct cap caps[slre.num_caps + 2];
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char nbuf[SLRE_PATSZ];
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const char *old;
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char *np;
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int i, olen;
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(void) memset(caps, 0, sizeof(caps));
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res = slre_match(&slre, datap, len, caps);
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debug("Result: %d\n", res);
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for (i = 0; i < slre.num_caps; i++) {
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if (caps[i].len > 0) {
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debug("Substring %d: [%.*s]\n", i,
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caps[i].len, caps[i].ptr);
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}
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}
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if (res == 0) {
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if (loop == 0) {
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printf("%s: No match\n", t);
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return 1;
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} else {
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break;
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}
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}
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debug("## MATCH ## %s\n", data);
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if (s == NULL) {
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printf("%s=%s\n", name, t);
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return 1;
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}
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old = caps[0].ptr;
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olen = caps[0].len;
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if (nlen + 1 >= SLRE_PATSZ) {
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printf("## error: pattern buffer overflow: have %d, need %d\n",
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SLRE_BUFSZ, nlen + 1);
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return 1;
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}
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strcpy(nbuf, s);
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debug("## SUBST(1) ## %s\n", nbuf);
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/*
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* Handle back references
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*
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* Support for \0 ... \9, where \0 is the
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* whole matched pattern (similar to &).
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*
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* Implementation is a bit simpleminded as
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* backrefs are substituted sequentially, one
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* by one. This will lead to somewhat
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* unexpected results if the replacement
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* strings contain any \N strings then then
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* may get substitued, too. We accept this
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* restriction for the sake of simplicity.
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*/
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for (i = 0; i < 10; ++i) {
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char backref[2] = {
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'\\',
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'0',
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};
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if (caps[i].len == 0)
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break;
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backref[1] += i;
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debug("## BACKREF %d: replace \"%.*s\" by \"%.*s\" in \"%s\"\n",
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i,
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2, backref,
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caps[i].len, caps[i].ptr,
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nbuf);
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for (np = nbuf;;) {
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char *p = memstr(np, nlen, backref, 2);
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if (p == NULL)
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break;
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np = substitute(np, &nlen,
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SLRE_PATSZ,
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backref, 2,
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caps[i].ptr, caps[i].len);
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if (np == NULL)
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return 1;
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}
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}
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debug("## SUBST(2) ## %s\n", nbuf);
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datap = substitute(datap, &len, SLRE_BUFSZ,
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old, olen,
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nbuf, nlen);
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if (datap == NULL)
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return 1;
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debug("## REMAINDER: %s\n", datap);
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debug("## RESULT: %s\n", data);
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if (!global)
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break;
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}
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debug("## FINAL (now setenv()) : %s\n", data);
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printf("%s=%s\n", name, data);
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return setenv(name, data);
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}
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#endif
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static int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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{
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ulong a, b;
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ulong value;
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int w;
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if (argc < 3)
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/*
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* We take 3, 5, or 6 arguments:
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* 3 : setexpr name value
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* 5 : setexpr name val1 op val2
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* setexpr name [g]sub r s
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* 6 : setexpr name [g]sub r s t
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*/
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/* > 6 already tested by max command args */
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if ((argc < 3) || (argc == 4))
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return CMD_RET_USAGE;
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w = cmd_get_data_size(argv[0], 4);
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@ -69,6 +320,19 @@ static int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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return 0;
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}
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/* 5 or 6 args (6 args only with [g]sub) */
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#ifdef CONFIG_REGEX
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/*
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* rexep handling: "setexpr name [g]sub r s [t]"
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* with 5 args, "t" will be NULL
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*/
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if (strcmp(argv[2], "gsub") == 0)
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return regex_sub(argv[1], argv[3], argv[4], argv[5], 1);
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if (strcmp(argv[2], "sub") == 0)
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return regex_sub(argv[1], argv[3], argv[4], argv[5], 0);
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#endif
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/* standard operators: "setexpr name val1 op val2" */
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if (argc != 5)
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return CMD_RET_USAGE;
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@ -114,13 +378,23 @@ static int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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}
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U_BOOT_CMD(
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setexpr, 5, 0, do_setexpr,
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setexpr, 6, 0, do_setexpr,
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"set environment variable as the result of eval expression",
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"[.b, .w, .l] name [*]value1 <op> [*]value2\n"
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" - set environment variable 'name' to the result of the evaluated\n"
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" express specified by <op>. <op> can be &, |, ^, +, -, *, /, %\n"
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" expression specified by <op>. <op> can be &, |, ^, +, -, *, /, %\n"
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" size argument is only meaningful if value1 and/or value2 are\n"
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" memory addresses (*)\n"
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"setexpr[.b, .w, .l] name [*]value\n"
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" - load a value into a variable"
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#ifdef CONFIG_REGEX
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"\n"
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"setexpr name gsub r s [t]\n"
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" - For each substring matching the regular expression <r> in the\n"
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" string <t>, substitute the string <s>. The result is\n"
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" assigned to <name>. If <t> is not supplied, use the old\n"
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" value of <name>\n"
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"setexpr name sub r s [t]\n"
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" - Just like gsub(), but replace only the first matching substring"
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#endif
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);
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