mirror of
https://github.com/isc-projects/bind9.git
synced 2026-05-28 04:34:54 -04:00
Speed up lib/dns/gen.c
The `gen` program was causing a lengthy single-threaded pause in the BIND build. When generating RDATATYPE_FROMTEXT_SW(), `gen` hit the inner loop of `find_typename()` over 1.2 billion times. This change avoids long deeply-nested loops, so `gen` now runs in less than 10ms, about 300x faster. No changes to the output.
This commit is contained in:
Tony Finch
Tony Finch
parent
6e9e4cdcb2
commit
96b6d78f75
2 changed files with 59 additions and 88 deletions
3
CHANGES
3
CHANGES
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@ -1,3 +1,6 @@
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6028. [performance] Build-time code generation of DNS RRtype switches
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is now much faster. [GL !7121]
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6027. [bug] Fix assertion failure in isc_http API used by
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statschannel if the read callback would be called
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on HTTP request that has been already closed.
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144
lib/dns/gen.c
144
lib/dns/gen.c
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@ -135,7 +135,7 @@ static const char copyright[] = "/*\n"
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static struct cc {
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struct cc *next;
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int rdclass;
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uint16_t rdclass;
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char classbuf[TYPECLASSBUF];
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} * classes;
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@ -152,11 +152,12 @@ static struct ttnam {
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char typebuf[TYPECLASSBUF];
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char macroname[TYPECLASSBUF];
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char attr[ATTRIBUTESIZE];
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unsigned int sorted;
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bool todo;
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uint8_t hash;
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uint16_t type;
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} typenames[TYPENAMES];
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static int maxtype = -1;
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static int ttnam_count;
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typedef struct {
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DIR *handle;
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@ -177,6 +178,19 @@ sd(unsigned int, const char *, const char *, char);
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static void
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insert_into_typenames(int, const char *, const char *);
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static uint8_t
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HASH(char *string) {
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size_t n;
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unsigned char a, b;
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n = strlen(string);
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INSIST(n > 0);
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a = tolower((unsigned char)string[0]);
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b = tolower((unsigned char)string[n - 1]);
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return (((a + n) * b) % 256);
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}
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static bool
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start_directory(const char *path, isc_dir_t *dir) {
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dir->handle = opendir(path);
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@ -336,18 +350,6 @@ doswitch(const char *name, const char *function, const char *args,
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}
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}
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static struct ttnam *
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find_typename(int type) {
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int i;
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for (i = 0; i < TYPENAMES; i++) {
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if (typenames[i].typebuf[0] != 0 && typenames[i].type == type) {
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return (&typenames[i]);
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}
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}
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return (NULL);
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}
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static void
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insert_into_typenames(int type, const char *typebuf, const char *attr) {
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struct ttnam *ttn = NULL;
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@ -356,22 +358,25 @@ insert_into_typenames(int type, const char *typebuf, const char *attr) {
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char tmp[256];
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INSIST(strlen(typebuf) < TYPECLASSBUF);
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for (i = 0; i < TYPENAMES; i++) {
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if (typenames[i].typebuf[0] != 0 && typenames[i].type == type &&
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strcmp(typebuf, typenames[i].typebuf) != 0)
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{
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for (i = 0; i < TYPENAMES && typenames[i].typebuf[0] != 0; i++) {
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if (typenames[i].type != type) {
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continue;
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}
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if (strcmp(typebuf, typenames[i].typebuf) != 0) {
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fprintf(stderr,
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"Error: type %d has two names: %s, %s\n", type,
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"Error: type %d has two names: %s, %s\n", type,
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typenames[i].typebuf, typebuf);
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exit(1);
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}
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if (typenames[i].typebuf[0] == 0 && ttn == NULL) {
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ttn = &typenames[i];
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}
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ttn = &typenames[i];
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}
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if (ttn == NULL) {
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/* Subtract one to leave an empty sentinel entry at the end */
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if (i >= TYPENAMES - 1) {
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fprintf(stderr, "Error: typenames array too small\n");
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exit(1);
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} else if (ttn == NULL) {
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ttn = &typenames[i];
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ttnam_count = i + 1;
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}
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/* XXXMUKS: This is redundant due to the INSIST above. */
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@ -419,10 +424,8 @@ insert_into_typenames(int type, const char *typebuf, const char *attr) {
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strncpy(ttn->attr, attr, sizeof(ttn->attr));
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ttn->attr[sizeof(ttn->attr) - 1] = '\0';
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ttn->sorted = 0;
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if (maxtype < type) {
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maxtype = type;
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}
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ttn->hash = HASH(ttn->typebuf);
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ttn->todo = true;
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}
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static void
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@ -469,16 +472,12 @@ add(unsigned int rdclass, const char *classbuf, int type, const char *typebuf,
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}
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while ((tt != NULL) && (tt->type == type) && (tt->rdclass < rdclass)) {
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if (strcmp(tt->typebuf, typebuf) != 0) {
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exit(1);
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}
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INSIST(strcmp(tt->typebuf, typebuf) == 0);
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oldtt = tt;
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tt = tt->next;
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}
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if ((tt != NULL) && (tt->type == type) && (tt->rdclass == rdclass)) {
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exit(1);
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}
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INSIST(tt == NULL || tt->type != type || tt->rdclass != rdclass);
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newtt->next = tt;
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if (oldtt != NULL) {
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@ -563,20 +562,10 @@ sd(unsigned int rdclass, const char *classbuf, const char *dirbuf,
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end_directory(&dir);
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}
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static unsigned int
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HASH(char *string) {
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size_t n;
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unsigned char a, b;
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n = strlen(string);
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if (n == 0) {
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fprintf(stderr, "n == 0?\n");
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exit(1);
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}
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a = tolower((unsigned char)string[0]);
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b = tolower((unsigned char)string[n - 1]);
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return (((a + n) * b) % 256);
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static int
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ttnam_cmp(const void *va, const void *vb) {
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const struct ttnam *ttna = va, *ttnb = vb;
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return (ttna->type - ttnb->type);
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}
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int
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@ -588,7 +577,6 @@ main(int argc, char **argv) {
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struct tt *tt;
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struct cc *cc;
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struct ttnam *ttn, *ttn2;
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unsigned int hash;
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time_t now;
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char year[11];
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int lasttype;
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@ -597,7 +585,7 @@ main(int argc, char **argv) {
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int type_enum = 0;
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int structs = 0;
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int depend = 0;
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int c, i, j, n;
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int c, n;
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char buf1[TYPECLASSBUF];
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char filetype = 'c';
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FILE *fd;
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@ -609,10 +597,6 @@ main(int argc, char **argv) {
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char *endptr;
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isc_dir_t dir;
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for (i = 0; i < TYPENAMES; i++) {
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memset(&typenames[i], 0, sizeof(typenames[i]));
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}
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srcdir[0] = '\0';
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while ((c = getopt(argc, argv, "cdits:F:P:S:")) != -1) {
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switch (c) {
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@ -676,9 +660,7 @@ main(int argc, char **argv) {
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n = snprintf(buf, sizeof(buf), "%srdata", srcdir);
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INSIST(n > 0 && (unsigned int)n < sizeof(srcdir));
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if (!start_directory(buf, &dir)) {
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exit(1);
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}
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INSIST(start_directory(buf, &dir));
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while (next_file(&dir)) {
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if (sscanf(dir.filename, TYPECLASSFMT, classbuf, &rdclass) != 2)
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@ -816,8 +798,6 @@ main(int argc, char **argv) {
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* attributes.
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*/
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#define PRINT_COMMA(x) (x == maxtype ? "" : ",")
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#define METANOTQUESTION \
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"DNS_RDATATYPEATTR_META | " \
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"DNS_RDATATYPEATTR_NOTQUESTION"
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@ -841,6 +821,12 @@ main(int argc, char **argv) {
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insert_into_typenames(254, "maila", METAQUESTIONONLY);
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insert_into_typenames(255, "any", METAQUESTIONONLY);
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/*
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* For reproducible builds, ensure the directory read
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* order does not affect the order of switch cases.
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*/
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qsort(typenames, ttnam_count, sizeof(struct ttnam), ttnam_cmp);
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/*
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* Spit out a quick and dirty hash function. Here,
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* we walk through the list of type names, and calculate
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@ -867,37 +853,27 @@ main(int argc, char **argv) {
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printf("#define RDATATYPE_FROMTEXT_SW(_hash,"
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"_typename,_length,_typep) \\\n");
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printf("\tswitch (_hash) { \\\n");
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for (i = 0; i <= maxtype; i++) {
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ttn = find_typename(i);
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if (ttn == NULL) {
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continue;
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}
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for (ttn = typenames; ttn->typebuf[0] != 0; ttn++) {
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/*
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* Skip entries we already processed.
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*/
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if (ttn->sorted != 0) {
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if (!ttn->todo) {
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continue;
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}
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hash = HASH(ttn->typebuf);
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printf("\t\tcase %u: \\\n", hash);
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printf("\t\tcase %u: \\\n", ttn->hash);
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/*
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* Find all other entries that happen to match
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* this hash.
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*/
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for (j = 0; j <= maxtype; j++) {
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ttn2 = find_typename(j);
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if (ttn2 == NULL) {
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continue;
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}
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if (hash == HASH(ttn2->typebuf)) {
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for (ttn2 = typenames; ttn2->typebuf[0] != 0; ttn2++) {
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if (ttn2->todo && ttn2->hash == ttn->hash) {
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printf("\t\t\tRDATATYPE_COMPARE"
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"(\"%s\", %d, _typename, "
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" _length, _typep); \\\n",
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ttn2->typebuf, ttn2->type);
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ttn2->sorted = 1;
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ttn2->todo = false;
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}
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}
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printf("\t\t\tbreak; \\\n");
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@ -906,35 +882,27 @@ main(int argc, char **argv) {
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printf("#define RDATATYPE_ATTRIBUTE_SW \\\n");
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printf("\tswitch (type) { \\\n");
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for (i = 0; i <= maxtype; i++) {
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ttn = find_typename(i);
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if (ttn == NULL) {
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continue;
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}
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printf("\tcase %d: return (%s); \\\n", i,
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for (ttn = typenames; ttn->typebuf[0] != 0; ttn++) {
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printf("\tcase %d: return (%s); \\\n", ttn->type,
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upper(ttn->attr));
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}
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printf("\t}\n");
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printf("#define RDATATYPE_TOTEXT_SW \\\n");
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printf("\tswitch (type) { \\\n");
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for (i = 0; i <= maxtype; i++) {
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ttn = find_typename(i);
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if (ttn == NULL) {
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continue;
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}
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for (ttn = typenames; ttn->typebuf[0] != 0; ttn++) {
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/*
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* Remove KEYDATA (65533) from the type to memonic
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* translation as it is internal use only. This
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* stops the tools from displaying KEYDATA instead
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* of TYPE65533.
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*/
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if (i == 65533U) {
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if (ttn->type == 65533U) {
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continue;
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}
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printf("\tcase %d: return "
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"(str_totext(\"%s\", target)); \\\n",
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i, upper(ttn->typebuf));
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ttn->type, upper(ttn->typebuf));
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}
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printf("\t}\n");
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} else if (type_enum) {
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