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-rw-r--r--tools/lib/bpf/strset.c176
1 files changed, 176 insertions, 0 deletions
diff --git a/tools/lib/bpf/strset.c b/tools/lib/bpf/strset.c
new file mode 100644
index 000000000000..1fb8b49de1d6
--- /dev/null
+++ b/tools/lib/bpf/strset.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2021 Facebook */
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <linux/err.h>
+#include "hashmap.h"
+#include "libbpf_internal.h"
+#include "strset.h"
+
+struct strset {
+ void *strs_data;
+ size_t strs_data_len;
+ size_t strs_data_cap;
+ size_t strs_data_max_len;
+
+ /* lookup index for each unique string in strings set */
+ struct hashmap *strs_hash;
+};
+
+static size_t strset_hash_fn(const void *key, void *ctx)
+{
+ const struct strset *s = ctx;
+ const char *str = s->strs_data + (long)key;
+
+ return str_hash(str);
+}
+
+static bool strset_equal_fn(const void *key1, const void *key2, void *ctx)
+{
+ const struct strset *s = ctx;
+ const char *str1 = s->strs_data + (long)key1;
+ const char *str2 = s->strs_data + (long)key2;
+
+ return strcmp(str1, str2) == 0;
+}
+
+struct strset *strset__new(size_t max_data_sz, const char *init_data, size_t init_data_sz)
+{
+ struct strset *set = calloc(1, sizeof(*set));
+ struct hashmap *hash;
+ int err = -ENOMEM;
+
+ if (!set)
+ return ERR_PTR(-ENOMEM);
+
+ hash = hashmap__new(strset_hash_fn, strset_equal_fn, set);
+ if (IS_ERR(hash))
+ goto err_out;
+
+ set->strs_data_max_len = max_data_sz;
+ set->strs_hash = hash;
+
+ if (init_data) {
+ long off;
+
+ set->strs_data = malloc(init_data_sz);
+ if (!set->strs_data)
+ goto err_out;
+
+ memcpy(set->strs_data, init_data, init_data_sz);
+ set->strs_data_len = init_data_sz;
+ set->strs_data_cap = init_data_sz;
+
+ for (off = 0; off < set->strs_data_len; off += strlen(set->strs_data + off) + 1) {
+ /* hashmap__add() returns EEXIST if string with the same
+ * content already is in the hash map
+ */
+ err = hashmap__add(hash, (void *)off, (void *)off);
+ if (err == -EEXIST)
+ continue; /* duplicate */
+ if (err)
+ goto err_out;
+ }
+ }
+
+ return set;
+err_out:
+ strset__free(set);
+ return ERR_PTR(err);
+}
+
+void strset__free(struct strset *set)
+{
+ if (IS_ERR_OR_NULL(set))
+ return;
+
+ hashmap__free(set->strs_hash);
+ free(set->strs_data);
+}
+
+size_t strset__data_size(const struct strset *set)
+{
+ return set->strs_data_len;
+}
+
+const char *strset__data(const struct strset *set)
+{
+ return set->strs_data;
+}
+
+static void *strset_add_str_mem(struct strset *set, size_t add_sz)
+{
+ return libbpf_add_mem(&set->strs_data, &set->strs_data_cap, 1,
+ set->strs_data_len, set->strs_data_max_len, add_sz);
+}
+
+/* Find string offset that corresponds to a given string *s*.
+ * Returns:
+ * - >0 offset into string data, if string is found;
+ * - -ENOENT, if string is not in the string data;
+ * - <0, on any other error.
+ */
+int strset__find_str(struct strset *set, const char *s)
+{
+ long old_off, new_off, len;
+ void *p;
+
+ /* see strset__add_str() for why we do this */
+ len = strlen(s) + 1;
+ p = strset_add_str_mem(set, len);
+ if (!p)
+ return -ENOMEM;
+
+ new_off = set->strs_data_len;
+ memcpy(p, s, len);
+
+ if (hashmap__find(set->strs_hash, (void *)new_off, (void **)&old_off))
+ return old_off;
+
+ return -ENOENT;
+}
+
+/* Add a string s to the string data. If the string already exists, return its
+ * offset within string data.
+ * Returns:
+ * - > 0 offset into string data, on success;
+ * - < 0, on error.
+ */
+int strset__add_str(struct strset *set, const char *s)
+{
+ long old_off, new_off, len;
+ void *p;
+ int err;
+
+ /* Hashmap keys are always offsets within set->strs_data, so to even
+ * look up some string from the "outside", we need to first append it
+ * at the end, so that it can be addressed with an offset. Luckily,
+ * until set->strs_data_len is incremented, that string is just a piece
+ * of garbage for the rest of the code, so no harm, no foul. On the
+ * other hand, if the string is unique, it's already appended and
+ * ready to be used, only a simple set->strs_data_len increment away.
+ */
+ len = strlen(s) + 1;
+ p = strset_add_str_mem(set, len);
+ if (!p)
+ return -ENOMEM;
+
+ new_off = set->strs_data_len;
+ memcpy(p, s, len);
+
+ /* Now attempt to add the string, but only if the string with the same
+ * contents doesn't exist already (HASHMAP_ADD strategy). If such
+ * string exists, we'll get its offset in old_off (that's old_key).
+ */
+ err = hashmap__insert(set->strs_hash, (void *)new_off, (void *)new_off,
+ HASHMAP_ADD, (const void **)&old_off, NULL);
+ if (err == -EEXIST)
+ return old_off; /* duplicated string, return existing offset */
+ if (err)
+ return err;
+
+ set->strs_data_len += len; /* new unique string, adjust data length */
+ return new_off;
+}