/* * 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 * * 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 , 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 #include #ifdef USE_HOSTCC /* HOST build */ # include # include # ifndef debug # ifdef DEBUG # define debug(fmt,args...) printf(fmt ,##args) # else # define debug(fmt,args...) # endif # endif #else /* U-Boot build */ # include # include #endif #ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */ #define CONFIG_ENV_MIN_ENTRIES 64 #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 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 { 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; } /* * 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() */ /* * 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 > 0) { 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(). */ int hmatch_r(const char *match, int last_idx, ENTRY ** retval, struct hsearch_data *htab) { unsigned int idx; size_t key_len = strlen(match); for (idx = last_idx + 1; idx < htab->size; ++idx) { if (htab->table[idx].used <= 0) continue; if (!strncmp(match, htab->table[idx].entry.key, key_len)) { *retval = &htab->table[idx].entry; return idx; } } __set_errno(ESRCH); *retval = NULL; return 0; } 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; unsigned int first_deleted = 0; /* 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 == -1 && !first_deleted) first_deleted = idx; 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 */ if (first_deleted) idx = first_deleted; 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_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 = -1; --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. */ 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 > 0) { 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_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. * On the other hand we need to add some more entries for free * space when importing very small buffers. Both boundaries can * be overwritten in the board config file if needed. */ if (!htab->table) { int nent = CONFIG_ENV_MIN_ENTRIES + 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 */ }