From 82c7a7a4baf4a7a15381ee720799dc41c3d54909 Mon Sep 17 00:00:00 2001
From: Vincent Sanders <vince@kyllikki.org>
Date: Tue, 31 Mar 2015 22:41:37 +0100
Subject: Fix RISC OS not having a pread/pwrite implementation.

---
 content/fs_backing_store.c |  6 ++++--
 utils/config.h             | 20 +++++++++++++++++---
 utils/utils.c              | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/content/fs_backing_store.c b/content/fs_backing_store.c
index 963fd5439..f2e6a387f 100644
--- a/content/fs_backing_store.c
+++ b/content/fs_backing_store.c
@@ -35,6 +35,8 @@
  *
  */
 
+#include "utils/config.h"
+
 #include <unistd.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -1606,7 +1608,7 @@ static nserror store_write_block(struct store_state *state,
 	     wr, bse->elem[elem_idx].size, bse->elem[elem_idx].data,
 	     offst, bse->elem[elem_idx].block));
 
-	if (wr != bse->elem[elem_idx].size) {
+	if (wr != (ssize_t)bse->elem[elem_idx].size) {
 		return NSERROR_SAVE_FAILED;
 	}
 
@@ -1754,7 +1756,7 @@ static nserror store_read_block(struct store_state *state,
 	     rd, bse->elem[elem_idx].size, bse->elem[elem_idx].data,
 	     offst, bse->elem[elem_idx].block));
 
-	if (rd != bse->elem[elem_idx].size) {
+	if (rd != (ssize_t)bse->elem[elem_idx].size) {
 		return NSERROR_SAVE_FAILED;
 	}
 
diff --git a/utils/config.h b/utils/config.h
index c45b865fe..cfb9d83c3 100644
--- a/utils/config.h
+++ b/utils/config.h
@@ -39,7 +39,7 @@ char *strcasestr(const char *haystack, const char *needle);
 #endif
 
 /* Although these platforms might have strftime or strptime they
- * appear not to support the time_t seconds format specifier.
+ *  appear not to support the time_t seconds format specifier.
  */
 #if (defined(_WIN32) || defined(riscos) || defined(__HAIKU__) || defined(__BEOS__) || defined(__amigaos4__) || defined(__AMIGA__) || defined(__MINT__))
 #undef HAVE_STRPTIME
@@ -49,8 +49,9 @@ char *strcasestr(const char *haystack, const char *needle);
 #define HAVE_STRFTIME
 #endif
 
-/* For some reason, UnixLib defines this unconditionally. 
- * Assume we're using UnixLib if building for RISC OS. */
+/* For some reason, UnixLib defines this unconditionally. Assume we're using
+ *  UnixLib if building for RISC OS.
+ */
 #if ((defined(_GNU_SOURCE) && !defined(__APPLE__)) || defined(riscos))
 #define HAVE_STRCHRNUL
 #else
@@ -58,6 +59,19 @@ char *strcasestr(const char *haystack, const char *needle);
 char *strchrnul(const char *s, int c);
 #endif
 
+/* Although these are in POSIX and implemented most places, RISC OS is
+ *  missing them.
+ */
+#if (defined(riscos))
+#undef HAVE_PREAD
+#undef HAVE_PWRITE
+ssize_t pread(int fd, void *buf, size_t count, off_t offset);
+ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
+#else
+#define HAVE_PREAD
+#define HAVE_PWRITE
+#endif
+
 #define HAVE_SYS_SELECT
 #define HAVE_INETATON
 #if (defined(_WIN32))
diff --git a/utils/utils.c b/utils/utils.c
index 5c8acd6f0..722e32302 100644
--- a/utils/utils.c
+++ b/utils/utils.c
@@ -32,6 +32,7 @@
 #include <regex.h>
 #include <time.h>
 #include <errno.h>
+#include <unistd.h>
 
 #include "utils/config.h"
 #include "utils/log.h"
@@ -628,3 +629,34 @@ nserror nsc_snptimet(char *str, size_t size, time_t *timep)
 
 	return NSERROR_OK;
 }
+
+#ifndef HAVE_PREAD
+
+ssize_t pread(int fd, void *buf, size_t count, off_t offset)
+{
+	off_t sk;
+
+	sk = lseek(fd, offset, SEEK_SET);
+	if (sk == -1) {
+		return (off_t)-1;
+	}
+	return read(fd, buf, count);
+}
+
+#endif
+
+
+#ifndef HAVE_PWRITE
+
+ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset)
+{
+	off_t sk;
+
+	sk = lseek(fd, offset, SEEK_SET);
+	if (sk == (off_t)-1) {
+		return -1;
+	}
+	return write(fd, buf, count);
+}
+
+#endif
-- 
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