mem: add mem helper functions

Signed-off-by: Cody P Schafer <dev@codyps.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

ccan/mem/mem.c

@@ -40,3 +40,27 @@ void *memrchr(const void *s, int c, size_t n)
 	return NULL;
 }
 #endif
+
+void *mempbrkm(const void *data_, size_t len, const void *accept_, size_t accept_len)
+{
+	const char *data = data_, *accept = accept_;
+	size_t i, j;
+
+	for (i = 0; i < len; i++)
+		for (j = 0; j < accept_len; j++)
+			if (accept[j] == data[i])
+				return (void *)&data[i];
+	return NULL;
+}
+
+void *memcchr(void const *data, int c, size_t data_len)
+{
+	char const *p = data;
+	size_t i;
+
+	for (i = 0; i < data_len; i++)
+		if (p[i] != c)
+			return (void *)&p[i];
+
+	return NULL;
+}

ccan/mem/mem.h

@@ -5,6 +5,7 @@
 #include "config.h"
 
 #include <string.h>
+#include <stdbool.h>
 
 #if !HAVE_MEMMEM
 void *memmem(const void *haystack, size_t haystacklen,
@@ -15,4 +16,160 @@ void *memmem(const void *haystack, size_t haystacklen,
 void *memrchr(const void *s, int c, size_t n);
 #endif
 
+/**
+ * mempbrkm - locates the first occurrence in @data of any bytes in @accept
+ * @data: where we search
+ * @len: length of data in bytes
+ * @accept: array of bytes we search for
+ * @accept_len: # of bytes in accept
+ *
+ * Returns a pointer to the byte in @data that matches one of the bytes in
+ * @accept, or NULL if no such byte is found.
+ *
+ * Example:
+ *	char otherbytes[] = "Hello \0world";
+ *	size_t otherbytes_len = sizeof(otherbytes) - 1;
+ *	char *r = mempbrkm(otherbytes, otherbytes_len, "\0b", 2);
+ *	if (r) {
+ *		printf("Found %c\n", *r);
+ *	} else {
+ *		printf("Nada\n");
+ *	}
+ *
+ */
+void *mempbrkm(const void *data, size_t len, const void *accept, size_t accept_len);
+
+/**
+ * mempbrk - locates the first occurrence in @data of any bytes in @accept
+ * @data: where we search
+ * @len: length of data in bytes
+ * @accept: NUL terminated string containing the bytes we search for
+ *
+ * Returns a pointer to the byte in @data that matches one of the bytes in
+ * @accept, or NULL if no such byte is found.
+ *
+ * Example:
+ *
+ *	r = mempbrk(otherbytes, otherbytes_len, "abcde");
+ *	if (r) {
+ *		printf("Found %c\n", *r);
+ *	} else {
+ *		printf("Nada\n");
+ *	}
+ */
+static inline char *mempbrk(const void *data, size_t len, const char *accept)
+{
+	return mempbrkm(data, len, accept, strlen(accept));
+}
+
+/**
+ * memcchr - scan memory until a character does _not_ match @c
+ * @data: pointer to memory to scan
+ * @data_len: length of data
+ * @c: character to scan for
+ *
+ * The complement of memchr().
+ *
+ * Returns a pointer to the first character which is _not_ @c. If all memory in
+ * @data is @c, returns NULL.
+ *
+ * Example:
+ *	char somebytes[] = "HI By\0e";
+ *	size_t bytes_len = sizeof(somebytes) - 1;
+ *	r = memcchr(somebytes, ' ', bytes_len);
+ *	if (r) {
+ *		printf("Found %c after trimming spaces\n", *r);
+ *	}
+ */
+void *memcchr(void const *data, int c, size_t data_len);
+
+/**
+ * memeq - Are two byte arrays equal?
+ * @a: first array
+ * @al: bytes in first array
+ * @b: second array
+ * @bl: bytes in second array
+ *
+ * Example:
+ *	if (memeq(somebytes, bytes_len, otherbytes, otherbytes_len)) {
+ *		printf("memory blocks are the same!\n");
+ *	}
+ */
+static inline bool memeq(const void *a, size_t al, const void *b, size_t bl)
+{
+	return al == bl && !memcmp(a, b, bl);
+}
+
+/**
+ * memstarts - determine if @data starts with @prefix
+ * @data: does this begin with @prefix?
+ * @data_len: bytes in @data
+ * @prefix: does @data begin with these bytes?
+ * @prefix_len: bytes in @prefix
+ *
+ * Returns true if @data starts with @prefix, otherwise return false.
+ *
+ * Example:
+ *	if (memstarts(somebytes, bytes_len, otherbytes, otherbytes_len)) {
+ *		printf("somebytes starts with otherbytes!\n");
+ *	}
+ */
+static inline bool memstarts(void const *data, size_t data_len,
+		void const *prefix, size_t prefix_len)
+{
+	if (prefix_len > data_len)
+		return false;
+	return memeq(data, prefix_len, prefix, prefix_len);
+}
+
+/**
+ * memeqstr - Is a byte array equal to a NUL terminated string?
+ * @data: byte array
+ * @length: length of @data in bytes
+ * @string: NUL terminated string
+ *
+ * The '\0' byte is ignored when checking if @bytes == @string.
+ *
+ * Example:
+ *	if (memeqstr(somebytes, bytes_len, "foo")) {
+ *		printf("somebytes == 'foo'!\n");
+ *	}
+ */
+static inline bool memeqstr(const void *data, size_t length, const char *string)
+{
+	return memeq(data, length, string, strlen(string));
+}
+
+/**
+ * memstarts_str - Does this byte array start with a string prefix?
+ * @a: byte array
+ * @al: length in bytes
+ * @s: string prefix
+ *
+ * Example:
+ *	if (memstarts_str(somebytes, bytes_len, "It")) {
+ *		printf("somebytes starts with 'It'\n");
+ *	}
+ */
+static inline bool memstarts_str(const void *a, size_t al, const char *s)
+{
+	return memstarts(a, al, s, strlen(s));
+}
+
+/**
+ * memends - Does this byte array end with a given byte-array suffix?
+ * @s: byte array
+ * @s_len: length in bytes
+ * @suffix: byte array suffix
+ * @suffix_len: length of suffix in bytes
+ *
+ * Returns true if @suffix appears as a substring at the end of @s,
+ * false otherwise.
+ */
+static inline bool memends(const void *s, size_t s_len, const void *suffix, size_t suffix_len)
+{
+	return (s_len >= suffix_len) && (memcmp((const char *)s + s_len - suffix_len,
+						suffix, suffix_len) == 0);
+}
+
 #endif /* CCAN_MEM_H */

ccan/mem/test/api.c

@@ -8,9 +8,11 @@ int main(void)
 	char haystack2[] = "ab\0ab\0ab\0ab";
 	char needle1[] = "ab";
 	char needle2[] = "d\0e";
+	char scan1[] = "aaaab";
+	char scan2[] = "\0\0\0b";
 
 	/* This is how many tests you plan to run */
-	plan_tests(19);
+	plan_tests(42);
 
 	ok1(memmem(haystack1, sizeof(haystack1), needle1, 2) == haystack1);
 	ok1(memmem(haystack1, sizeof(haystack1), needle1, 3) == NULL);
@@ -37,6 +39,39 @@ int main(void)
 
 	ok1(memrchr(needle1, '\0', 2) == NULL);
 
+#define S(x) (x), sizeof(x) - 1
+	ok1(mempbrkm(S(haystack1), S("\0efgh")) == haystack1 + 4);
+	ok1(mempbrkm(S(haystack1), S("jklmn")) == NULL);
+	ok1(mempbrkm(S(haystack1), S("sd\0a")) == haystack1 + 0);
+
+	ok1(mempbrk(haystack1, sizeof(haystack1), "bcd\0a") == haystack1 + 1);
+	ok1(mempbrk(haystack1, sizeof(haystack1), "\0") == NULL);
+
+	ok1(memcchr(scan1, 'a', sizeof(scan1)) == scan1 + 4);
+	ok1(memcchr(scan1, 'b', sizeof(scan1)) == scan1);
+	ok1(memcchr(scan2, '\0', sizeof(scan2)) == scan2 + 3);
+	ok1(memcchr(scan2, '\0', sizeof(scan2) - 2) == NULL);
+
+	ok1(memeq(haystack1, sizeof(haystack1), haystack1, sizeof(haystack1)));
+	ok1(!memeq(haystack1, sizeof(haystack1), haystack2, sizeof(haystack2)));
+
+	ok1(memeqstr(scan1, sizeof(scan1) - 1, scan1));
+	ok1(!memeqstr(scan1, sizeof(scan1), scan1));
+	ok1(!memeqstr(scan1, sizeof(scan1), "aaaa"));
+
+	ok1(memstarts(S("a\0bcdef"), S("a\0bc")));
+	ok1(!memstarts(S("a\0bcdef"), S("a\0bcG")));
+	ok1(!memstarts(S("a\0bcdef"), S("a\0bcdefg")));
+
+	ok1(memstarts_str(scan1, sizeof(scan1), scan1));
+	ok1(!memstarts_str(scan1, sizeof(scan1), "ab"));
+
+	ok1(memends(S("abcdef"), S("abcdef")));
+	ok1(!memends(S("abcdef"), S("abcdefg")));
+	ok1(!memends(S("a\0bcdef"), S("a\0b")));
+	ok1(memends(S("a\0bcdef"), S("ef")));
+
+
 	/* This exits depending on whether all tests passed */
 	return exit_status();
 }