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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-07 22:13:13 (GMT)
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-07 22:13:13 (GMT)
commite83c5163316f89bfbde7d9ab23ca2e25604af290 (patch)
tree2b5bfdf7798569e0b59b16eb9602d5fa572d6038 /cache.h
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Initial revision of "git", the information manager from hell
Diffstat (limited to 'cache.h')
-rw-r--r--cache.h93
1 files changed, 93 insertions, 0 deletions
diff --git a/cache.h b/cache.h
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index 0000000..98a32a9
--- /dev/null
+++ b/cache.h
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+#ifndef CACHE_H
+#define CACHE_H
+
+#include <stdio.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <errno.h>
+#include <sys/mman.h>
+
+#include <openssl/sha.h>
+#include <zlib.h>
+
+/*
+ * Basic data structures for the directory cache
+ *
+ * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
+ * not even trying to be portable. It's trying to be efficient. It's
+ * just a cache, after all.
+ */
+
+#define CACHE_SIGNATURE 0x44495243 /* "DIRC" */
+struct cache_header {
+ unsigned int signature;
+ unsigned int version;
+ unsigned int entries;
+ unsigned char sha1[20];
+};
+
+/*
+ * The "cache_time" is just the low 32 bits of the
+ * time. It doesn't matter if it overflows - we only
+ * check it for equality in the 32 bits we save.
+ */
+struct cache_time {
+ unsigned int sec;
+ unsigned int nsec;
+};
+
+/*
+ * dev/ino/uid/gid/size are also just tracked to the low 32 bits
+ * Again - this is just a (very strong in practice) heuristic that
+ * the inode hasn't changed.
+ */
+struct cache_entry {
+ struct cache_time ctime;
+ struct cache_time mtime;
+ unsigned int st_dev;
+ unsigned int st_ino;
+ unsigned int st_mode;
+ unsigned int st_uid;
+ unsigned int st_gid;
+ unsigned int st_size;
+ unsigned char sha1[20];
+ unsigned short namelen;
+ unsigned char name[0];
+};
+
+const char *sha1_file_directory;
+struct cache_entry **active_cache;
+unsigned int active_nr, active_alloc;
+
+#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
+#define DEFAULT_DB_ENVIRONMENT ".dircache/objects"
+
+#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
+#define ce_size(ce) cache_entry_size((ce)->namelen)
+
+#define alloc_nr(x) (((x)+16)*3/2)
+
+/* Initialize the cache information */
+extern int read_cache(void);
+
+/* Return a statically allocated filename matching the sha1 signature */
+extern char *sha1_file_name(unsigned char *sha1);
+
+/* Write a memory buffer out to the sha file */
+extern int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size);
+
+/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
+extern void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size);
+extern int write_sha1_file(char *buf, unsigned len);
+
+/* Convert to/from hex/sha1 representation */
+extern int get_sha1_hex(char *hex, unsigned char *sha1);
+extern char *sha1_to_hex(unsigned char *sha1); /* static buffer! */
+
+/* General helper functions */
+extern void usage(const char *err);
+
+#endif /* CACHE_H */