thodg/libgit2/tests/object/raw/short.c

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• Hash : 31ecaca2
  Author :
  Date : 2021-09-30T08:11:40
  

  hash: hash functions operate on byte arrays not git_oids Separate the concerns of the hash functions from the git_oid functions. The git_oid structure will need to understand either SHA1 or SHA256; the hash functions should only deal with the appropriate one of these.

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• tests/object/raw/short.c

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  #include "clar_libgit2.h"
  
  #include "odb.h"
  #include "hash.h"
  
  void test_object_raw_short__oid_shortener_no_duplicates(void)
  {
  	git_oid_shorten *os;
  	int min_len;
  
  	os = git_oid_shorten_new(0);
  	cl_assert(os != NULL);
  
  	git_oid_shorten_add(os, "22596363b3de40b06f981fb85d82312e8c0ed511");
  	git_oid_shorten_add(os, "ce08fe4884650f067bd5703b6a59a8b3b3c99a09");
  	git_oid_shorten_add(os, "16a0123456789abcdef4b775213c23a8bd74f5e0");
  	min_len = git_oid_shorten_add(os, "ce08fe4884650f067bd5703b6a59a8b3b3c99a09");
  
  	cl_assert(min_len == GIT_OID_HEXSZ + 1);
  
  	git_oid_shorten_free(os);
  }
  
  static int insert_sequential_oids(
  	char ***out, git_oid_shorten *os, int n, int fail)
  {
  	int i, min_len = 0;
  	char numbuf[16];
  	git_oid oid;
  	char **oids = git__calloc(n, sizeof(char *));
  	cl_assert(oids != NULL);
  
  	for (i = 0; i < n; ++i) {
  		p_snprintf(numbuf, sizeof(numbuf), "%u", (unsigned int)i);
  		git_hash_buf(oid.id, numbuf, strlen(numbuf), GIT_HASH_ALGORITHM_SHA1);
  
  		oids[i] = git__malloc(GIT_OID_HEXSZ + 1);
  		cl_assert(oids[i]);
  		git_oid_nfmt(oids[i], GIT_OID_HEXSZ + 1, &oid);
  
  		min_len = git_oid_shorten_add(os, oids[i]);
  
  		/* After "fail", we expect git_oid_shorten_add to fail */
  		if (fail >= 0 && i >= fail)
              cl_assert(min_len < 0);
  		else
              cl_assert(min_len >= 0);
  	}
  
  	*out = oids;
  
  	return min_len;
  }
  
  static void free_oids(int n, char **oids)
  {
  	int i;
  
  	for (i = 0; i < n; ++i) {
  		git__free(oids[i]);
  	}
  	git__free(oids);
  }
  
  void test_object_raw_short__oid_shortener_stresstest_git_oid_shorten(void)
  {
  #define MAX_OIDS 1000
  
  	git_oid_shorten *os;
  	size_t i, j;
  	int min_len = 0, found_collision;
  	char **oids;
  
  	os = git_oid_shorten_new(0);
  	cl_assert(os != NULL);
  
  	/*
  	 * Insert in the shortener 1000 unique SHA1 ids
  	 */
  	min_len = insert_sequential_oids(&oids, os, MAX_OIDS, MAX_OIDS);
  	cl_assert(min_len > 0);
  
  	/*
  	 * Compare the first `min_char - 1` characters of each
  	 * SHA1 OID. If the minimizer worked, we should find at
  	 * least one collision
  	 */
  	found_collision = 0;
  	for (i = 0; i < MAX_OIDS; ++i) {
  		for (j = i + 1; j < MAX_OIDS; ++j) {
  			if (memcmp(oids[i], oids[j], min_len - 1) == 0)
  				found_collision = 1;
  		}
  	}
  	cl_assert_equal_b(true, found_collision);
  
  	/*
  	 * Compare the first `min_char` characters of each
  	 * SHA1 OID. If the minimizer worked, every single preffix
  	 * should be unique.
  	 */
  	found_collision = 0;
  	for (i = 0; i < MAX_OIDS; ++i) {
  		for (j = i + 1; j < MAX_OIDS; ++j) {
  			if (memcmp(oids[i], oids[j], min_len) == 0)
  				found_collision = 1;
  		}
  	}
  	cl_assert_equal_b(false, found_collision);
  
  	/* cleanup */
  	free_oids(MAX_OIDS, oids);
  	git_oid_shorten_free(os);
  
  #undef MAX_OIDS
  }
  
  void test_object_raw_short__oid_shortener_too_much_oids(void)
  {
      /* The magic number of oids at which an oid_shortener will fail.
       * This was experimentally established. */
  #define MAX_OIDS 24556
  
  	git_oid_shorten *os;
  	char **oids;
  
  	os = git_oid_shorten_new(0);
  	cl_assert(os != NULL);
  
  	cl_assert(insert_sequential_oids(&oids, os, MAX_OIDS, MAX_OIDS - 1) < 0);
  
  	free_oids(MAX_OIDS, oids);
  	git_oid_shorten_free(os);
  
  #undef MAX_OIDS
  }
  

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