Handle partial reads and errors in package IO (RhBug:802839, RhBug:580974)

- There are no guarantees Fread() will return all of the requested size:
  it can return partial data eg on signals and pipe descriptors. Introduce
  a helper function to handle this centrally for all package read IO,
  effectively reintroducing timedRead() but without the caveats:
  timedRead() did not work on compressed streams, did not handle
  eg EINTR correctly and while really being an internal helper,
  was exported in the API.

lib/header.c

@@ -964,7 +964,7 @@ Header headerRead(FD_t fd, int magicp)
     if (magicp == HEADER_MAGIC_YES) {
 	int32_t magic;
 
-	if (Fread(block, 1, 4*sizeof(*block), fd) != 4*sizeof(*block))
+	if (Freadall(fd, block, 4*sizeof(*block)) != 4*sizeof(*block))
 	    goto exit;
 
 	magic = block[0];
@@ -975,7 +975,7 @@ Header headerRead(FD_t fd, int magicp)
 	il = ntohl(block[2]);
 	dl = ntohl(block[3]);
     } else {
-	if (Fread(block, 1, 2*sizeof(*block), fd) != 2*sizeof(*block))
+	if (Freadall(fd, block, 2*sizeof(*block)) != 2*sizeof(*block))
 	    goto exit;
 
 	il = ntohl(block[0]);
@@ -993,7 +993,7 @@ Header headerRead(FD_t fd, int magicp)
     ei[0] = htonl(il);
     ei[1] = htonl(dl);
 
-    if (Fread((char *)&ei[2], 1, blen, fd) != blen)
+    if (Freadall(fd, (char *)&ei[2], blen) != blen)
 	goto exit;
     
     h = headerImport(ei, len, 0);
@@ -1747,3 +1747,29 @@ void headerSetInstance(Header h, unsigned int instance)
     h->instance = instance;
 }    
 
+#define RETRY_ERROR(_err) \
+    ((_err) == EINTR || (_err) == EAGAIN || (_err) == EWOULDBLOCK)
+
+ssize_t Freadall(FD_t fd, void * buf, ssize_t size)
+{
+    ssize_t total = 0;
+    ssize_t nb = 0;
+    char * bufp = buf;
+
+    while (total < size) {
+	nb = Fread(bufp, 1, size - total, fd);
+
+	if (nb == 0 || (nb < 0 && !RETRY_ERROR(errno))) {
+	    total = nb;
+	    break;
+	}
+
+	if (nb > 0) {
+	    bufp += nb;
+	    total += nb;
+	}
+    }
+
+    return total;
+}
+

lib/header_internal.h

@@ -72,6 +72,9 @@ extern "C" {
 RPM_GNUC_INTERNAL
 void headerSetInstance(Header h, unsigned int instance);
 
+/* Package IO helper to consolidate partial read and error handling */
+RPM_GNUC_INTERNAL
+ssize_t Freadall(FD_t fd, void * buf, ssize_t size);
 #ifdef __cplusplus
 }   
 #endif

lib/package.c

@@ -422,7 +422,7 @@ static rpmRC rpmpkgReadHeader(rpmKeyring keyring, rpmVSFlags vsflags,
 	*msg = NULL;
 
     memset(block, 0, sizeof(block));
-    if ((xx = Fread(block, 1, sizeof(block), fd)) != sizeof(block)) {
+    if ((xx = Freadall(fd, block, sizeof(block))) != sizeof(block)) {
 	rasprintf(&buf, 
 		_("hdr size(%d): BAD, read returned %d\n"), (int)sizeof(block), xx);
 	goto exit;
@@ -448,7 +448,7 @@ static rpmRC rpmpkgReadHeader(rpmKeyring keyring, rpmVSFlags vsflags,
     ei = xmalloc(uc);
     ei[0] = block[2];
     ei[1] = block[3];
-    if ((xx = Fread((char *)&ei[2], 1, nb, fd)) != nb) {
+    if ((xx = Freadall(fd, (char *)&ei[2], nb)) != nb) {
 	rasprintf(&buf, _("hdr blob(%zd): BAD, read returned %d\n"), nb, xx);
 	goto exit;
     }

lib/rpmlead.c

@@ -12,6 +12,7 @@
 #include <rpm/rpmstring.h>
 
 #include "lib/signature.h"
+#include "lib/header_internal.h"	/* Freadall() */
 #include "lib/rpmlead.h"
 
 #include "debug.h"
@@ -117,7 +118,7 @@ rpmRC rpmLeadRead(FD_t fd, rpmlead *lead, int *type, char **emsg)
     char *err = NULL;
 
     memset(&l, 0, sizeof(l));
-    if (Fread(&l, 1, sizeof(l), fd) != sizeof(l)) {
+    if (Freadall(fd, &l, sizeof(l)) != sizeof(l)) {
 	if (Ferror(fd)) {
 	    rasprintf(&err, _("read failed: %s (%d)\n"), Fstrerror(fd), errno);
 	    rc = RPMRC_FAIL;

lib/signature.c

@@ -86,7 +86,7 @@ rpmRC rpmReadSignature(FD_t fd, Header * sighp, sigType sig_type, char ** msg)
 	goto exit;
 
     memset(block, 0, sizeof(block));
-    if ((xx = Fread(block, 1, sizeof(block), fd)) != sizeof(block)) {
+    if ((xx = Freadall(fd, block, sizeof(block))) != sizeof(block)) {
 	rasprintf(&buf, _("sigh size(%d): BAD, read returned %d\n"), 
 		  (int)sizeof(block), xx);
 	goto exit;
@@ -118,7 +118,7 @@ rpmRC rpmReadSignature(FD_t fd, Header * sighp, sigType sig_type, char ** msg)
     ei[1] = block[3];
     pe = (entryInfo) &ei[2];
     dataStart = (unsigned char *) (pe + il);
-    if ((xx = Fread(pe, 1, nb, fd)) != nb) {
+    if ((xx = Freadall(fd, pe, nb)) != nb) {
 	rasprintf(&buf,
 		  _("sigh blob(%d): BAD, read returned %d\n"), (int)nb, xx);
 	goto exit;
@@ -214,7 +214,7 @@ rpmRC rpmReadSignature(FD_t fd, Header * sighp, sigType sig_type, char ** msg)
 	rpm_loff_t archSize = 0;
 
 	/* Position at beginning of header. */
-	if (pad && (trc = Fread(block, 1, pad, fd)) != pad) {
+	if (pad && (trc = Freadall(fd, block, pad)) != pad) {
 	    rasprintf(&buf,
 		      _("sigh pad(%zd): BAD, read %zd bytes\n"), pad, trc);
 	    goto exit;