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path: root/blame.c
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#include <assert.h>
 
#include "cache.h"
#include "refs.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "epoch.h"
#include "diff.h"
 
#define DEBUG 0
 
struct commit** blame_lines;
int num_blame_lines;
 
struct util_info
{
    int* line_map;
    int num_lines;
    unsigned char sha1[20]; /* blob sha, not commit! */
    char* buf;
    unsigned long size;
//    const char* path;
};
 
struct chunk
{
    int off1, len1; // ---
    int off2, len2; // +++
};
 
struct patch
{
    struct chunk* chunks;
    int num;
};
 
static void get_blob(struct commit* commit);
 
int num_get_patch = 0;
int num_commits = 0;
 
struct patch* get_patch(struct commit* commit, struct commit* other)
{
    struct patch* ret = xmalloc(sizeof(struct patch));
    ret->chunks = NULL;
    ret->num = 0;
 
    struct util_info* info_c = (struct util_info*) commit->object.util;
    struct util_info* info_o = (struct util_info*) other->object.util;
 
    if(!memcmp(info_c->sha1, info_o->sha1, 20))
        return ret;
 
    get_blob(commit);
    get_blob(other);
 
    FILE* fout = fopen("/tmp/git-blame-tmp1", "w");
    if(!fout)
        die("fopen tmp1 failed: %s", strerror(errno));
 
    if(fwrite(info_c->buf, info_c->size, 1, fout) != 1)
        die("fwrite 1 failed: %s", strerror(errno));
    fclose(fout);
 
    fout = fopen("/tmp/git-blame-tmp2", "w");
    if(!fout)
        die("fopen tmp2 failed: %s", strerror(errno));
 
    if(fwrite(info_o->buf, info_o->size, 1, fout) != 1)
        die("fwrite 2 failed: %s", strerror(errno));
    fclose(fout);
 
    FILE* fin = popen("diff -u0 /tmp/git-blame-tmp1 /tmp/git-blame-tmp2", "r");
    if(!fin)
        die("popen failed: %s", strerror(errno));
 
    char buf[1024];
    while(fgets(buf, sizeof(buf), fin)) {
        if(buf[0] != '@' || buf[1] != '@')
            continue;
 
        if(DEBUG)
            printf("chunk line: %s", buf);
        ret->num++;
        ret->chunks = xrealloc(ret->chunks, sizeof(struct chunk)*ret->num);
        struct chunk* chunk = &ret->chunks[ret->num-1];
 
        assert(!strncmp(buf, "@@ -", 4));
 
        char* start = buf+4;
        char* sp = index(start, ' ');
        *sp = '\0';
        if(index(start, ',')) {
            int ret = sscanf(start, "%d,%d", &chunk->off1, &chunk->len1);
            assert(ret == 2);
        } else {
            int ret = sscanf(start, "%d", &chunk->off1);
            assert(ret == 1);
            chunk->len1 = 1;
        }
        *sp = ' ';
 
        start = sp+1;
        sp = index(start, ' ');
        *sp = '\0';
        if(index(start, ',')) {
            int ret = sscanf(start, "%d,%d", &chunk->off2, &chunk->len2);
            assert(ret == 2);
        } else {
            int ret = sscanf(start, "%d", &chunk->off2);
            assert(ret == 1);
            chunk->len2 = 1;
        }
        *sp = ' ';
 
        if(chunk->off1 > 0)
            chunk->off1 -= 1;
        if(chunk->off2 > 0)
            chunk->off2 -= 1;
 
        assert(chunk->off1 >= 0);
        assert(chunk->off2 >= 0);
    }
    fclose(fin);
 
    num_get_patch++;
    return ret;
}
 
void free_patch(struct patch* p)
{
    free(p->chunks);
    free(p);
}
 
static int get_blob_sha1_internal(unsigned char *sha1, const char *base, int baselen,
                                  const char *pathname, unsigned mode, int stage);
 
 
static unsigned char blob_sha1[20];
static int get_blob_sha1(struct tree* t, const char* pathname, unsigned char* sha1)
{
    const char *pathspec[2];
    pathspec[0] = pathname;
    pathspec[1] = NULL;
    memset(blob_sha1, 0, sizeof(blob_sha1));
    read_tree_recursive(t, "", 0, 0, pathspec, get_blob_sha1_internal);
 
    int i;
    for(i = 0; i < 20; i++) {
        if(blob_sha1[i] != 0)
            break;
    }
 
    if(i == 20)
        return -1;
 
    memcpy(sha1, blob_sha1, 20);
    return 0;
}
 
static int get_blob_sha1_internal(unsigned char *sha1, const char *base, int baselen,
                                  const char *pathname, unsigned mode, int stage)
{
//    printf("Got blob: %s base: '%s' baselen: %d pathname: '%s' mode: %o stage: %d\n",
//           sha1_to_hex(sha1), base, baselen, pathname, mode, stage);
 
    if(S_ISDIR(mode))
        return READ_TREE_RECURSIVE;
 
    memcpy(blob_sha1, sha1, 20);
    return -1;
}
 
static void get_blob(struct commit* commit)
{
    struct util_info* info = commit->object.util;
    char type[20];
 
    if(info->buf)
        return;
 
    info->buf = read_sha1_file(info->sha1, type, &info->size);
    assert(!strcmp(type, "blob"));
}
 
void print_patch(struct patch* p)
{
    printf("Num chunks: %d\n", p->num);
    int i;
    for(i = 0; i < p->num; i++) {
        printf("%d,%d %d,%d\n", p->chunks[i].off1, p->chunks[i].len1, p->chunks[i].off2, p->chunks[i].len2);
    }
}
 
 
// p is a patch from commit to other.
void fill_line_map(struct commit* commit, struct commit* other, struct patch* p)
{
    int num_lines = ((struct util_info*) commit->object.util)->num_lines;
    int* line_map = ((struct util_info*) commit->object.util)->line_map;
    int num_lines2 = ((struct util_info*) other->object.util)->num_lines;
    int* line_map2 = ((struct util_info*) other->object.util)->line_map;
    int cur_chunk = 0;
    int i1, i2;
 
    if(p->num && DEBUG)
        print_patch(p);
 
    for(i1 = 0; i1 < num_lines; i1++)
        line_map[i1] = -1;
 
    if(DEBUG)
        printf("num lines 1: %d num lines 2: %d\n", num_lines, num_lines2);
 
    for(i1 = 0, i2 = 0; i1 < num_lines; i1++, i2++) {
        if(DEBUG > 1)
            printf("%d %d\n", i1, i2);
 
        if(i2 >= num_lines2)
            break;
 
        line_map[i1] = line_map2[i2];
 
        struct chunk* chunk = NULL;
        if(cur_chunk < p->num)
            chunk = &p->chunks[cur_chunk];
 
        if(chunk && chunk->off1 == i1) {
            i2 = chunk->off2;
 
            if(chunk->len1 > 0)
                i1 += chunk->len1-1;
            if(chunk->len2 > 0)
                i2 += chunk->len2-1;
            cur_chunk++;
        }
    }
}
 
int map_line(struct commit* commit, int line)
{
    struct util_info* info = commit->object.util;
    assert(line >= 0 && line < info->num_lines);
    return info->line_map[line];
}
 
int fill_util_info(struct commit* commit, const char* path)
{
    if(commit->object.util)
        return 0;
 
    struct util_info* util = xmalloc(sizeof(struct util_info));
    util->buf = NULL;
    util->size = 0;
    util->num_lines = -1;
    util->line_map = NULL;
 
    commit->object.util = util;
 
    if(get_blob_sha1(commit->tree, path, util->sha1))
        return -1;
 
    return 0;
}
 
void alloc_line_map(struct commit* commit)
{
    struct util_info* util = commit->object.util;
 
    if(util->line_map)
        return;
 
    get_blob(commit);
 
    int i;
    util->num_lines = 0;
    for(i = 0; i < util->size; i++) {
        if(util->buf[i] == '\n')
            util->num_lines++;
    }
    util->line_map = xmalloc(sizeof(int)*util->num_lines);
}
 
void copy_line_map(struct commit* dst, struct commit* src)
{
    struct util_info* u_dst = dst->object.util;
    struct util_info* u_src = src->object.util;
 
    u_dst->line_map = u_src->line_map;
    u_dst->num_lines = u_src->num_lines;
    u_dst->buf = u_src->buf;
    u_dst->size = u_src->size;
}
 
void process_commits(struct commit_list* list, const char* path)
{
    int i;
 
    while(list) {
        struct commit* commit = pop_commit(&list);
        struct commit_list* parents;
        struct util_info* info;
 
        info = commit->object.util;
        num_commits++;
        if(DEBUG)
            printf("\nProcessing commit: %d %s\n", num_commits, sha1_to_hex(commit->object.sha1));
        for(parents = commit->parents;
            parents != NULL; parents = parents->next) {
            struct commit* parent = parents->item;
 
            if(parse_commit(parent) < 0)
                die("parse_commit error");
 
            if(DEBUG)
                printf("parent: %s\n", sha1_to_hex(parent->object.sha1));
 
            if(fill_util_info(parent, path))
                continue;
 
            // Temporarily assign everything to the parent.
            int num_blame = 0;
            for(i = 0; i < num_blame_lines; i++) {
                if(blame_lines[i] == commit) {
                    num_blame++;
                    blame_lines[i] = parent;
                }
            }
 
            if(num_blame == 0)
                continue;
 
            struct patch* patch = get_patch(parent, commit);
            if(patch->num == 0) {
                copy_line_map(parent, commit);
            } else {
                alloc_line_map(parent);
                fill_line_map(parent, commit, patch);
            }
 
            for(i = 0; i < patch->num; i++) {
                int l;
                for(l = 0; l < patch->chunks[i].len2; l++) {
                    int mapped_line = map_line(commit, patch->chunks[i].off2 + l);
                    if(mapped_line != -1 && blame_lines[mapped_line] == parent)
                        blame_lines[mapped_line] = commit;
                }
            }
            free_patch(patch);
        }
    }
}
 
#define SEEN 1
struct commit_list* get_commit_list(struct commit* commit, const char* pathname)
{
    struct commit_list* ret = NULL;
    struct commit_list* process = NULL;
    unsigned char sha1[20];
 
    commit_list_insert(commit, &process);
 
    while(process) {
        struct commit* com = pop_commit(&process);
        if(com->object.flags & SEEN)
            continue;
 
        com->object.flags |= SEEN;
        commit_list_insert(com, &ret);
        struct commit_list* parents;
 
        parse_commit(com);
 
        for(parents = com->parents;
            parents != NULL; parents = parents->next) {
            struct commit* parent = parents->item;
 
            parse_commit(parent);
 
            if(!get_blob_sha1(parent->tree, pathname, sha1))
                commit_list_insert(parent, &process);
        }
    }
 
    return ret;
}
 
int main(int argc, const char **argv)
{
    unsigned char sha1[20];
    struct commit *commit;
    const char* filename;
    int i;
 
    setup_git_directory();
 
    if (argc != 3)
        die("Usage: blame commit-ish file");
 
    if (get_sha1(argv[1], sha1))
        die("get_sha1 failed");
 
    commit = lookup_commit_reference(sha1);
 
    filename = argv[2];
 
    struct commit_list* list = get_commit_list(commit, filename);
    sort_in_topological_order(&list, 1);
 
    if(fill_util_info(commit, filename)) {
        printf("%s not found in %s\n", filename, argv[1]);
        return 0;
    }
    alloc_line_map(commit);
 
    struct util_info* util = commit->object.util;
    num_blame_lines = util->num_lines;
    blame_lines = xmalloc(sizeof(struct commit*)*num_blame_lines);
 
 
    for(i = 0; i < num_blame_lines; i++) {
        blame_lines[i] = commit;
 
        ((struct util_info*) commit->object.util)->line_map[i] = i;
    }
 
    process_commits(list, filename);
 
    for(i = 0; i < num_blame_lines; i++) {
        printf("%d %s\n", i+1-1, sha1_to_hex(blame_lines[i]->object.sha1));
//        printf("%d %s\n", i+1-1, find_unique_abbrev(blame_lines[i]->object.sha1, 6));
    }
 
    if(DEBUG) {
        printf("num get patch: %d\n", num_get_patch);
        printf("num commits: %d\n", num_commits);
    }
 
    return 0;
}