summaryrefslogtreecommitdiff
path: root/lib/hashtable.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/hashtable.c')
-rw-r--r--lib/hashtable.c735
1 files changed, 735 insertions, 0 deletions
diff --git a/lib/hashtable.c b/lib/hashtable.c
new file mode 100644
index 000000000..b747f1f79
--- /dev/null
+++ b/lib/hashtable.c
@@ -0,0 +1,735 @@
+/*
+ * This implementation is based on code from uClibc-0.9.30.3 but was
+ * modified and extended for use within U-Boot.
+ *
+ * Copyright (C) 2010 Wolfgang Denk <wd@denx.de>
+ *
+ * Original license header:
+ *
+ * Copyright (C) 1993, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
+ * This file is part of the GNU C Library.
+ * Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993.
+ *
+ * The GNU C Library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * The GNU C Library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with the GNU C Library; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA.
+ */
+
+#include <errno.h>
+#include <malloc.h>
+
+#ifdef USE_HOSTCC /* HOST build */
+# include <string.h>
+# include <assert.h>
+
+# ifndef debug
+# ifdef DEBUG
+# define debug(fmt,args...) printf(fmt ,##args)
+# else
+# define debug(fmt,args...)
+# endif
+# endif
+#else /* U-Boot build */
+# include <common.h>
+# include <linux/string.h>
+#endif
+
+#ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
+#define CONFIG_ENV_MAX_ENTRIES 512
+#endif
+
+#include "search.h"
+
+/*
+ * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
+ * [Knuth] The Art of Computer Programming, part 3 (6.4)
+ */
+
+/*
+ * The non-reentrant version use a global space for storing the hash table.
+ */
+static struct hsearch_data htab;
+
+/*
+ * The reentrant version has no static variables to maintain the state.
+ * Instead the interface of all functions is extended to take an argument
+ * which describes the current status.
+ */
+typedef struct _ENTRY {
+ unsigned int used;
+ ENTRY entry;
+} _ENTRY;
+
+
+/*
+ * hcreate()
+ */
+
+/*
+ * For the used double hash method the table size has to be a prime. To
+ * correct the user given table size we need a prime test. This trivial
+ * algorithm is adequate because
+ * a) the code is (most probably) called a few times per program run and
+ * b) the number is small because the table must fit in the core
+ * */
+static int isprime(unsigned int number)
+{
+ /* no even number will be passed */
+ unsigned int div = 3;
+
+ while (div * div < number && number % div != 0)
+ div += 2;
+
+ return number % div != 0;
+}
+
+int hcreate(size_t nel)
+{
+ return hcreate_r(nel, &htab);
+}
+
+/*
+ * Before using the hash table we must allocate memory for it.
+ * Test for an existing table are done. We allocate one element
+ * more as the found prime number says. This is done for more effective
+ * indexing as explained in the comment for the hsearch function.
+ * The contents of the table is zeroed, especially the field used
+ * becomes zero.
+ */
+int hcreate_r(size_t nel, struct hsearch_data *htab)
+{
+ /* Test for correct arguments. */
+ if (htab == NULL) {
+ __set_errno(EINVAL);
+ return 0;
+ }
+
+ /* There is still another table active. Return with error. */
+ if (htab->table != NULL)
+ return 0;
+
+ /* Change nel to the first prime number not smaller as nel. */
+ nel |= 1; /* make odd */
+ while (!isprime(nel))
+ nel += 2;
+
+ htab->size = nel;
+ htab->filled = 0;
+
+ /* allocate memory and zero out */
+ htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY));
+ if (htab->table == NULL)
+ return 0;
+
+ /* everything went alright */
+ return 1;
+}
+
+
+/*
+ * hdestroy()
+ */
+void hdestroy(void)
+{
+ hdestroy_r(&htab);
+}
+
+/*
+ * After using the hash table it has to be destroyed. The used memory can
+ * be freed and the local static variable can be marked as not used.
+ */
+void hdestroy_r(struct hsearch_data *htab)
+{
+ int i;
+
+ /* Test for correct arguments. */
+ if (htab == NULL) {
+ __set_errno(EINVAL);
+ return;
+ }
+
+ /* free used memory */
+ for (i = 1; i <= htab->size; ++i) {
+ if (htab->table[i].used) {
+ ENTRY *ep = &htab->table[i].entry;
+
+ free(ep->key);
+ free(ep->data);
+ }
+ }
+ free(htab->table);
+
+ /* the sign for an existing table is an value != NULL in htable */
+ htab->table = NULL;
+}
+
+/*
+ * hsearch()
+ */
+
+/*
+ * This is the search function. It uses double hashing with open addressing.
+ * The argument item.key has to be a pointer to an zero terminated, most
+ * probably strings of chars. The function for generating a number of the
+ * strings is simple but fast. It can be replaced by a more complex function
+ * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
+ *
+ * We use an trick to speed up the lookup. The table is created by hcreate
+ * with one more element available. This enables us to use the index zero
+ * special. This index will never be used because we store the first hash
+ * index in the field used where zero means not used. Every other value
+ * means used. The used field can be used as a first fast comparison for
+ * equality of the stored and the parameter value. This helps to prevent
+ * unnecessary expensive calls of strcmp.
+ *
+ * This implementation differs from the standard library version of
+ * this function in a number of ways:
+ *
+ * - While the standard version does not make any assumptions about
+ * the type of the stored data objects at all, this implementation
+ * works with NUL terminated strings only.
+ * - Instead of storing just pointers to the original objects, we
+ * create local copies so the caller does not need to care about the
+ * data any more.
+ * - The standard implementation does not provide a way to update an
+ * existing entry. This version will create a new entry or update an
+ * existing one when both "action == ENTER" and "item.data != NULL".
+ * - Instead of returning 1 on success, we return the index into the
+ * internal hash table, which is also guaranteed to be positive.
+ * This allows us direct access to the found hash table slot for
+ * example for functions like hdelete().
+ */
+
+ENTRY *hsearch(ENTRY item, ACTION action)
+{
+ ENTRY *result;
+
+ (void) hsearch_r(item, action, &result, &htab);
+
+ return result;
+}
+
+int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
+ struct hsearch_data *htab)
+{
+ unsigned int hval;
+ unsigned int count;
+ unsigned int len = strlen(item.key);
+ unsigned int idx;
+
+ /* Compute an value for the given string. Perhaps use a better method. */
+ hval = len;
+ count = len;
+ while (count-- > 0) {
+ hval <<= 4;
+ hval += item.key[count];
+ }
+
+ /*
+ * First hash function:
+ * simply take the modul but prevent zero.
+ */
+ hval %= htab->size;
+ if (hval == 0)
+ ++hval;
+
+ /* The first index tried. */
+ idx = hval;
+
+ if (htab->table[idx].used) {
+ /*
+ * Further action might be required according to the
+ * action value.
+ */
+ unsigned hval2;
+
+ if (htab->table[idx].used == hval
+ && strcmp(item.key, htab->table[idx].entry.key) == 0) {
+ /* Overwrite existing value? */
+ if ((action == ENTER) && (item.data != NULL)) {
+ free(htab->table[idx].entry.data);
+ htab->table[idx].entry.data =
+ strdup(item.data);
+ if (!htab->table[idx].entry.data) {
+ __set_errno(ENOMEM);
+ *retval = NULL;
+ return 0;
+ }
+ }
+ /* return found entry */
+ *retval = &htab->table[idx].entry;
+ return idx;
+ }
+
+ /*
+ * Second hash function:
+ * as suggested in [Knuth]
+ */
+ hval2 = 1 + hval % (htab->size - 2);
+
+ do {
+ /*
+ * Because SIZE is prime this guarantees to
+ * step through all available indices.
+ */
+ if (idx <= hval2)
+ idx = htab->size + idx - hval2;
+ else
+ idx -= hval2;
+
+ /*
+ * If we visited all entries leave the loop
+ * unsuccessfully.
+ */
+ if (idx == hval)
+ break;
+
+ /* If entry is found use it. */
+ if ((htab->table[idx].used == hval)
+ && strcmp(item.key, htab->table[idx].entry.key) == 0) {
+ /* Overwrite existing value? */
+ if ((action == ENTER) && (item.data != NULL)) {
+ free(htab->table[idx].entry.data);
+ htab->table[idx].entry.data =
+ strdup(item.data);
+ if (!htab->table[idx].entry.data) {
+ __set_errno(ENOMEM);
+ *retval = NULL;
+ return 0;
+ }
+ }
+ /* return found entry */
+ *retval = &htab->table[idx].entry;
+ return idx;
+ }
+ }
+ while (htab->table[idx].used);
+ }
+
+ /* An empty bucket has been found. */
+ if (action == ENTER) {
+ /*
+ * If table is full and another entry should be
+ * entered return with error.
+ */
+ if (htab->filled == htab->size) {
+ __set_errno(ENOMEM);
+ *retval = NULL;
+ return 0;
+ }
+
+ /*
+ * Create new entry;
+ * create copies of item.key and item.data
+ */
+ htab->table[idx].used = hval;
+ htab->table[idx].entry.key = strdup(item.key);
+ htab->table[idx].entry.data = strdup(item.data);
+ if (!htab->table[idx].entry.key ||
+ !htab->table[idx].entry.data) {
+ __set_errno(ENOMEM);
+ *retval = NULL;
+ return 0;
+ }
+
+ ++htab->filled;
+
+ /* return new entry */
+ *retval = &htab->table[idx].entry;
+ return 1;
+ }
+
+ __set_errno(ESRCH);
+ *retval = NULL;
+ return 0;
+}
+
+
+/*
+ * hdelete()
+ */
+
+/*
+ * The standard implementation of hsearch(3) does not provide any way
+ * to delete any entries from the hash table. We extend the code to
+ * do that.
+ */
+
+int hdelete(const char *key)
+{
+ return hdelete_r(key, &htab);
+}
+
+int hdelete_r(const char *key, struct hsearch_data *htab)
+{
+ ENTRY e, *ep;
+ int idx;
+
+ debug("hdelete: DELETE key \"%s\"\n", key);
+
+ e.key = (char *)key;
+
+ if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) {
+ __set_errno(ESRCH);
+ return 0; /* not found */
+ }
+
+ /* free used ENTRY */
+ debug("hdelete: DELETING key \"%s\"\n", key);
+
+ free(ep->key);
+ free(ep->data);
+ htab->table[idx].used = 0;
+
+ --htab->filled;
+
+ return 1;
+}
+
+/*
+ * hexport()
+ */
+
+/*
+ * Export the data stored in the hash table in linearized form.
+ *
+ * Entries are exported as "name=value" strings, separated by an
+ * arbitrary (non-NUL, of course) separator character. This allows to
+ * use this function both when formatting the U-Boot environment for
+ * external storage (using '\0' as separator), but also when using it
+ * for the "printenv" command to print all variables, simply by using
+ * as '\n" as separator. This can also be used for new features like
+ * exporting the environment data as text file, including the option
+ * for later re-import.
+ *
+ * The entries in the result list will be sorted by ascending key
+ * values.
+ *
+ * If the separator character is different from NUL, then any
+ * separator characters and backslash characters in the values will
+ * be escaped by a preceeding backslash in output. This is needed for
+ * example to enable multi-line values, especially when the output
+ * shall later be parsed (for example, for re-import).
+ *
+ * There are several options how the result buffer is handled:
+ *
+ * *resp size
+ * -----------
+ * NULL 0 A string of sufficient length will be allocated.
+ * NULL >0 A string of the size given will be
+ * allocated. An error will be returned if the size is
+ * not sufficient. Any unused bytes in the string will
+ * be '\0'-padded.
+ * !NULL 0 The user-supplied buffer will be used. No length
+ * checking will be performed, i. e. it is assumed that
+ * the buffer size will always be big enough. DANGEROUS.
+ * !NULL >0 The user-supplied buffer will be used. An error will
+ * be returned if the size is not sufficient. Any unused
+ * bytes in the string will be '\0'-padded.
+ */
+
+ssize_t hexport(const char sep, char **resp, size_t size)
+{
+ return hexport_r(&htab, sep, resp, size);
+}
+
+static int cmpkey(const void *p1, const void *p2)
+{
+ ENTRY *e1 = *(ENTRY **) p1;
+ ENTRY *e2 = *(ENTRY **) p2;
+
+ return (strcmp(e1->key, e2->key));
+}
+
+ssize_t hexport_r(struct hsearch_data *htab, const char sep,
+ char **resp, size_t size)
+{
+ ENTRY *list[htab->size];
+ char *res, *p;
+ size_t totlen;
+ int i, n;
+
+ /* Test for correct arguments. */
+ if ((resp == NULL) || (htab == NULL)) {
+ __set_errno(EINVAL);
+ return (-1);
+ }
+
+ debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %d\n",
+ htab, htab->size, htab->filled, size);
+ /*
+ * Pass 1:
+ * search used entries,
+ * save addresses and compute total length
+ */
+ for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
+
+ if (htab->table[i].used) {
+ ENTRY *ep = &htab->table[i].entry;
+
+ list[n++] = ep;
+
+ totlen += strlen(ep->key) + 2;
+
+ if (sep == '\0') {
+ totlen += strlen(ep->data);
+ } else { /* check if escapes are needed */
+ char *s = ep->data;
+
+ while (*s) {
+ ++totlen;
+ /* add room for needed escape chars */
+ if ((*s == sep) || (*s == '\\'))
+ ++totlen;
+ ++s;
+ }
+ }
+ totlen += 2; /* for '=' and 'sep' char */
+ }
+ }
+
+#ifdef DEBUG
+ /* Pass 1a: print unsorted list */
+ printf("Unsorted: n=%d\n", n);
+ for (i = 0; i < n; ++i) {
+ printf("\t%3d: %p ==> %-10s => %s\n",
+ i, list[i], list[i]->key, list[i]->data);
+ }
+#endif
+
+ /* Sort list by keys */
+ qsort(list, n, sizeof(ENTRY *), cmpkey);
+
+ /* Check if the user supplied buffer size is sufficient */
+ if (size) {
+ if (size < totlen + 1) { /* provided buffer too small */
+ debug("### buffer too small: %d, but need %d\n",
+ size, totlen + 1);
+ __set_errno(ENOMEM);
+ return (-1);
+ }
+ } else {
+ size = totlen + 1;
+ }
+
+ /* Check if the user provided a buffer */
+ if (*resp) {
+ /* yes; clear it */
+ res = *resp;
+ memset(res, '\0', size);
+ } else {
+ /* no, allocate and clear one */
+ *resp = res = calloc(1, size);
+ if (res == NULL) {
+ __set_errno(ENOMEM);
+ return (-1);
+ }
+ }
+ /*
+ * Pass 2:
+ * export sorted list of result data
+ */
+ for (i = 0, p = res; i < n; ++i) {
+ char *s;
+
+ s = list[i]->key;
+ while (*s)
+ *p++ = *s++;
+ *p++ = '=';
+
+ s = list[i]->data;
+
+ while (*s) {
+ if ((*s == sep) || (*s == '\\'))
+ *p++ = '\\'; /* escape */
+ *p++ = *s++;
+ }
+ *p++ = sep;
+ }
+ *p = '\0'; /* terminate result */
+
+ return size;
+}
+
+
+/*
+ * himport()
+ */
+
+/*
+ * Import linearized data into hash table.
+ *
+ * This is the inverse function to hexport(): it takes a linear list
+ * of "name=value" pairs and creates hash table entries from it.
+ *
+ * Entries without "value", i. e. consisting of only "name" or
+ * "name=", will cause this entry to be deleted from the hash table.
+ *
+ * The "flag" argument can be used to control the behaviour: when the
+ * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
+ * new data will be added to an existing hash table; otherwise, old
+ * data will be discarded and a new hash table will be created.
+ *
+ * The separator character for the "name=value" pairs can be selected,
+ * so we both support importing from externally stored environment
+ * data (separated by NUL characters) and from plain text files
+ * (entries separated by newline characters).
+ *
+ * To allow for nicely formatted text input, leading white space
+ * (sequences of SPACE and TAB chars) is ignored, and entries starting
+ * (after removal of any leading white space) with a '#' character are
+ * considered comments and ignored.
+ *
+ * [NOTE: this means that a variable name cannot start with a '#'
+ * character.]
+ *
+ * When using a non-NUL separator character, backslash is used as
+ * escape character in the value part, allowing for example for
+ * multi-line values.
+ *
+ * In theory, arbitrary separator characters can be used, but only
+ * '\0' and '\n' have really been tested.
+ */
+
+int himport(const char *env, size_t size, const char sep, int flag)
+{
+ return himport_r(&htab, env, size, sep, flag);
+}
+
+int himport_r(struct hsearch_data *htab,
+ const char *env, size_t size, const char sep, int flag)
+{
+ char *data, *sp, *dp, *name, *value;
+
+ /* Test for correct arguments. */
+ if (htab == NULL) {
+ __set_errno(EINVAL);
+ return 0;
+ }
+
+ /* we allocate new space to make sure we can write to the array */
+ if ((data = malloc(size)) == NULL) {
+ debug("himport_r: can't malloc %d bytes\n", size);
+ __set_errno(ENOMEM);
+ return 0;
+ }
+ memcpy(data, env, size);
+ dp = data;
+
+ if ((flag & H_NOCLEAR) == 0) {
+ /* Destroy old hash table if one exists */
+ debug("Destroy Hash Table: %p table = %p\n", htab,
+ htab->table);
+ if (htab->table)
+ hdestroy_r(htab);
+ }
+
+ /*
+ * Create new hash table (if needed). The computation of the hash
+ * table size is based on heuristics: in a sample of some 70+
+ * existing systems we found an average size of 39+ bytes per entry
+ * in the environment (for the whole key=value pair). Assuming a
+ * size of 8 per entry (= safety factor of ~5) should provide enough
+ * safety margin for any existing environment definitions and still
+ * allow for more than enough dynamic additions. Note that the
+ * "size" argument is supposed to give the maximum enviroment size
+ * (CONFIG_ENV_SIZE). This heuristics will result in
+ * unreasonably large numbers (and thus memory footprint) for
+ * big flash environments (>8,000 entries for 64 KB
+ * envrionment size), so we clip it to a reasonable value
+ * (which can be overwritten in the board config file if
+ * needed).
+ */
+
+ if (!htab->table) {
+ int nent = size / 8;
+
+ if (nent > CONFIG_ENV_MAX_ENTRIES)
+ nent = CONFIG_ENV_MAX_ENTRIES;
+
+ debug("Create Hash Table: N=%d\n", nent);
+
+ if (hcreate_r(nent, htab) == 0) {
+ free(data);
+ return 0;
+ }
+ }
+
+ /* Parse environment; allow for '\0' and 'sep' as separators */
+ do {
+ ENTRY e, *rv;
+
+ /* skip leading white space */
+ while ((*dp == ' ') || (*dp == '\t'))
+ ++dp;
+
+ /* skip comment lines */
+ if (*dp == '#') {
+ while (*dp && (*dp != sep))
+ ++dp;
+ ++dp;
+ continue;
+ }
+
+ /* parse name */
+ for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp)
+ ;
+
+ /* deal with "name" and "name=" entries (delete var) */
+ if (*dp == '\0' || *(dp + 1) == '\0' ||
+ *dp == sep || *(dp + 1) == sep) {
+ if (*dp == '=')
+ *dp++ = '\0';
+ *dp++ = '\0'; /* terminate name */
+
+ debug("DELETE CANDIDATE: \"%s\"\n", name);
+
+ if (hdelete_r(name, htab) == 0)
+ debug("DELETE ERROR ##############################\n");
+
+ continue;
+ }
+ *dp++ = '\0'; /* terminate name */
+
+ /* parse value; deal with escapes */
+ for (value = sp = dp; *dp && (*dp != sep); ++dp) {
+ if ((*dp == '\\') && *(dp + 1))
+ ++dp;
+ *sp++ = *dp;
+ }
+ *sp++ = '\0'; /* terminate value */
+ ++dp;
+
+ /* enter into hash table */
+ e.key = name;
+ e.data = value;
+
+ hsearch_r(e, ENTER, &rv, htab);
+ if (rv == NULL) {
+ printf("himport_r: can't insert \"%s=%s\" into hash table\n",
+ name, value);
+ return 0;
+ }
+
+ debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
+ htab, htab->filled, htab->size,
+ rv, name, value);
+ } while ((dp < data + size) && *dp); /* size check needed for text */
+ /* without '\0' termination */
+ debug("INSERT: free(data = %p)\n", data);
+ free(data);
+
+ debug("INSERT: done\n");
+ return 1; /* everything OK */
+}
generated by cgit v1.2.3-70-g09d2 (git 2.51.2) at 2025-10-31 20:47:51 +0000