[PATCH] Various transport programs

This patch adds three similar and related programs. http-pull downloads
objects from an HTTP server; rpull downloads objects by using ssh and
rpush on the other side; and rpush uploads objects by using ssh and rpull
on the other side.

The algorithm should be sufficient to make the network throughput required
depend only on how much content is new, not at all on how much content the
repository contains.

The combination should enable people to have remote repositories by way of
ssh login for authenticated users and HTTP for anonymous access.

Signed-Off-By: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

http-pull.c

@@ -0,0 +1,204 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include "cache.h"
+#include "commit.h"
+#include <errno.h>
+#include <stdio.h>
+
+#include <curl/curl.h>
+#include <curl/easy.h>
+
+static CURL *curl;
+
+static char *base;
+
+static int tree = 0;
+static int commits = 0;
+static int all = 0;
+
+static SHA_CTX c;
+static z_stream stream;
+
+static int local;
+static int zret;
+
+static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb, 
+			       void *data) {
+	char expn[4096];
+	size_t size = eltsize * nmemb;
+	int posn = 0;
+	do {
+		ssize_t retval = write(local, ptr + posn, size - posn);
+		if (retval < 0)
+			return posn;
+		posn += retval;
+	} while (posn < size);
+
+	stream.avail_in = size;
+	stream.next_in = ptr;
+	do {
+		stream.next_out = expn;
+		stream.avail_out = sizeof(expn);
+		zret = inflate(&stream, Z_SYNC_FLUSH);
+		SHA1_Update(&c, expn, sizeof(expn) - stream.avail_out);
+	} while (stream.avail_in && zret == Z_OK);
+	return size;
+}
+
+static int fetch(unsigned char *sha1)
+{
+	char *hex = sha1_to_hex(sha1);
+	char *filename = sha1_file_name(sha1);
+	char real_sha1[20];
+	char *url;
+	char *posn;
+
+	if (has_sha1_file(sha1)) {
+		return 0;
+	}
+
+	local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
+
+	if (local < 0)
+		return error("Couldn't open %s\n", filename);
+
+	memset(&stream, 0, sizeof(stream));
+
+	inflateInit(&stream);
+
+	SHA1_Init(&c);
+
+	curl_easy_setopt(curl, CURLOPT_FILE, NULL);
+	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
+
+	url = malloc(strlen(base) + 50);
+	strcpy(url, base);
+	posn = url + strlen(base);
+	strcpy(posn, "objects/");
+	posn += 8;
+	memcpy(posn, hex, 2);
+	posn += 2;
+	*(posn++) = '/';
+	strcpy(posn, hex + 2);
+
+	curl_easy_setopt(curl, CURLOPT_URL, url);
+
+	/*printf("Getting %s\n", hex);*/
+
+	if (curl_easy_perform(curl))
+		return error("Couldn't get %s for %s\n", url, hex);
+
+	close(local);
+	inflateEnd(&stream);
+	SHA1_Final(real_sha1, &c);
+	if (zret != Z_STREAM_END) {
+		unlink(filename);
+		return error("File %s (%s) corrupt\n", hex, url);
+	}
+	if (memcmp(sha1, real_sha1, 20)) {
+		unlink(filename);
+		return error("File %s has bad hash\n", hex);
+	}
+	
+	return 0;
+}
+
+static int process_tree(unsigned char *sha1)
+{
+	struct tree *tree = lookup_tree(sha1);
+	struct tree_entry_list *entries;
+
+	if (parse_tree(tree))
+		return -1;
+
+	for (entries = tree->entries; entries; entries = entries->next) {
+		if (fetch(entries->item.tree->object.sha1))
+			return -1;
+		if (entries->directory) {
+			if (process_tree(entries->item.tree->object.sha1))
+				return -1;
+		}
+	}
+	return 0;
+}
+
+static int process_commit(unsigned char *sha1)
+{
+	struct commit *obj = lookup_commit(sha1);
+
+	if (fetch(sha1))
+		return -1;
+
+	if (parse_commit(obj))
+		return -1;
+
+	if (tree) {
+		if (fetch(obj->tree->object.sha1))
+			return -1;
+		if (process_tree(obj->tree->object.sha1))
+			return -1;
+		if (!all)
+			tree = 0;
+	}
+	if (commits) {
+		struct commit_list *parents = obj->parents;
+		for (; parents; parents = parents->next) {
+			if (has_sha1_file(parents->item->object.sha1))
+				continue;
+			if (fetch(parents->item->object.sha1)) {
+				/* The server might not have it, and
+				 * we don't mind. 
+				 */
+				continue;
+			}
+			if (process_commit(parents->item->object.sha1))
+				return -1;
+		}
+	}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	char *commit_id;
+	char *url;
+	int arg = 1;
+	unsigned char sha1[20];
+
+	while (arg < argc && argv[arg][0] == '-') {
+		if (argv[arg][1] == 't') {
+			tree = 1;
+		} else if (argv[arg][1] == 'c') {
+			commits = 1;
+		} else if (argv[arg][1] == 'a') {
+			all = 1;
+			tree = 1;
+			commits = 1;
+		}
+		arg++;
+	}
+	if (argc < arg + 2) {
+		usage("http-pull [-c] [-t] [-a] commit-id url");
+		return 1;
+	}
+	commit_id = argv[arg];
+	url = argv[arg + 1];
+
+	get_sha1_hex(commit_id, sha1);
+
+	curl_global_init(CURL_GLOBAL_ALL);
+
+	curl = curl_easy_init();
+
+	base = url;
+
+	if (fetch(sha1))
+		return 1;
+	if (process_commit(sha1))
+		return 1;
+
+	curl_global_cleanup();
+	return 0;
+}