Improve changelog handling through addition of open/read/close functions

Thanks to Allan for inspiring all this work on what was one little TODO item
in the codebase. :)

Change changelog handling so we can now dump a changelog from both installed
packages and package files (fixes FS#7371). We do this by moving all of the
machinery to the backend where it should have been in the first place.

The changelog reading is now done through a open/read/close interface
similar to the fopen/fread/fclose functions (can you guess how it is done?).
It is buffered by the frontend, so programs using the library can read as
much or as little as they want at a time.

Unfortunately, I could not implement a changelog_feof function due to some
shortcomings of libarchive. However, I left the stub code in there,
commented out, in case it becomes possible later or anyone wants to take a
stab at it.

Original-work-by: Allan McRae <mcrae_allan@hotmail.com>
Improved-by: Chantry Xavier <shiningxc@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>

3 files changed, 23 insertions, 26 deletions

diff --git a/src/pacman/package.c b/src/pacman/package.c
index ac3f8207..ba572141 100644
--- a/src/pacman/package.c
+++ b/src/pacman/package.c
@@ -34,6 +34,8 @@
 #include "package.h"
 #include "util.h"
 
+#define CLBUF_SIZE 4096
+
 /* Display the content of a package
  *
  * level: <0 - sync package [-Si]
@@ -232,28 +234,30 @@ void dump_pkg_files(pmpkg_t *pkg)
 	fflush(stdout);
 }
 
-/* Display the changelog of an installed package
+/* Display the changelog of a package
  */
-void dump_pkg_changelog(char *clfile, const char *pkgname)
+void dump_pkg_changelog(pmpkg_t *pkg)
 {
-	FILE* fp = NULL;
-	char line[PATH_MAX+1];
+	void *fp = NULL;
 
-	if((fp = fopen(clfile, "r")) == NULL)
-	{
-		fprintf(stderr, _("error: no changelog available for '%s'.\n"), pkgname);
+	if((fp = alpm_pkg_changelog_open(pkg)) == NULL) {
+		/* TODO after string freeze use pm_fprintf */
+		fprintf(stderr, _("error: no changelog available for '%s'.\n"),
+				alpm_pkg_get_name(pkg));
 		return;
-	}
-	else
-	{
-		while(!feof(fp))
-		{
-			fgets(line, (int)PATH_MAX, fp);
-			printf("%s", line);
-			line[0] = '\0';
+	} else {
+		/* allocate a buffer to get the changelog back in chunks */
+		char buf[CLBUF_SIZE];
+		int ret = 0;
+		while((ret = alpm_pkg_changelog_read(buf, CLBUF_SIZE, pkg, fp))) {
+			if(ret < CLBUF_SIZE) {
+				/* if we hit the end of the file, we need to add a null terminator */
+				*(buf + ret) = '\0';
+			}
+			printf("%s", buf);
 		}
-		fclose(fp);
-		return;
+		alpm_pkg_changelog_close(pkg, fp);
+		printf("\n");
 	}
 }
 
diff --git a/src/pacman/package.h b/src/pacman/package.h
index 0e4bb0fa..7dfc0548 100644
--- a/src/pacman/package.h
+++ b/src/pacman/package.h
@@ -28,7 +28,7 @@ void dump_pkg_sync(pmpkg_t *pkg, const char *treename);
 
 void dump_pkg_backups(pmpkg_t *pkg);
 void dump_pkg_files(pmpkg_t *pkg);
-void dump_pkg_changelog(char *clfile, const char *pkgname);
+void dump_pkg_changelog(pmpkg_t *pkg);
 
 #endif /* _PM_PACKAGE_H */
 
diff --git a/src/pacman/query.c b/src/pacman/query.c
index 8a8765b6..13070772 100644
--- a/src/pacman/query.c
+++ b/src/pacman/query.c
@@ -312,14 +312,7 @@ static void display(pmpkg_t *pkg)
 		dump_pkg_files(pkg);
 	}
 	if(config->op_q_changelog) {
-		char changelog[PATH_MAX];
-		/* TODO should be done in the backend- no raw DB stuff up front */
-		snprintf(changelog, PATH_MAX, "%s/%s/%s-%s/changelog",
-				alpm_option_get_dbpath(),
-				alpm_db_get_name(db_local),
-				alpm_pkg_get_name(pkg),
-				alpm_pkg_get_version(pkg));
-		dump_pkg_changelog(changelog, alpm_pkg_get_name(pkg));
+		dump_pkg_changelog(pkg);
 	}
 	if(!config->op_q_info && !config->op_q_list && !config->op_q_changelog) {
 		if (!config->quiet) {