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-rw-r--r--common.h6
-rw-r--r--config.mk6
-rw-r--r--sum_fd.c32
-rw-r--r--update.c2
4 files changed, 45 insertions, 1 deletions
diff --git a/common.h b/common.h
index ad3be05..864082c 100644
--- a/common.h
+++ b/common.h
@@ -4,11 +4,17 @@
#include <sys/stat.h>
#include <alloca.h>
#include <errno.h>
+#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
+#ifndef ALLOCA_LIMIT
+# define ALLOCA_LIMIT 0
+#endif
+
+
/**
* Process a chunk using SHA-1 or SHA-0
*
diff --git a/config.mk b/config.mk
index 2062ea6..66efe55 100644
--- a/config.mk
+++ b/config.mk
@@ -6,3 +6,9 @@ CC = c99
CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700
CFLAGS = -Wall -O3
LDFLAGS = -s
+
+# You can add -DALLOCA_LIMIT=# to CPPFLAGS, where # is a size_t
+# value, to put a limit on how large allocation the library is
+# allowed to make with alloca(3). For buffers that can have any
+# size this limit will be used if it wants to allocate a larger
+# buffer. Choose 0 to use malloc(3) instead of alloca(3).
diff --git a/sum_fd.c b/sum_fd.c
index bc2761d..a61bf71 100644
--- a/sum_fd.c
+++ b/sum_fd.c
@@ -16,17 +16,42 @@ libsha1_sum_fd(int fd, enum libsha1_algorithm algorithm, void *restrict hashsum)
{
struct libsha1_state state;
ssize_t r;
+#ifndef _WIN32
struct stat attr;
+#endif
size_t blksize = 4096;
char *restrict chunk;
if (libsha1_init(&state, algorithm) < 0)
return -1;
+#ifndef _WIN32
if (fstat(fd, &attr) == 0 && attr.st_blksize > 0)
blksize = (size_t)(attr.st_blksize);
+#endif
+#if ALLOCA_LIMIT > 0
+ if (blksize > (size_t)ALLOCA_LIMIT) {
+ blksize = (size_t)ALLOCA_LIMIT;
+ blksize -= blksize % sizeof(((struct libsha1_state)NULL)->chunk);
+ if (!blksize)
+ blksize = sizeof(((struct libsha1_state)NULL)->chunk);
+ }
+# if defined(__clang__)
+ /* We are using a limit so it's just like declaring an array
+ * in a function, except we might use less of the stack. */
+# pragma clang diagnostic push
+# pragma clang diagnostic ignored "-Walloca"
+# endif
chunk = alloca(blksize);
+# if defined(__clang__)
+# pragma clang diagnostic pop
+# endif
+#else
+ chunk = malloc(blksize);
+ if (!chunk)
+ return -1;
+#endif
for (;;) {
r = read(fd, chunk, blksize);
@@ -35,11 +60,18 @@ libsha1_sum_fd(int fd, enum libsha1_algorithm algorithm, void *restrict hashsum)
break;
if (errno == EINTR)
continue;
+#if ALLOCA_LIMIT <= 0
+ free(chunk);
+#endif
return -1;
}
libsha1_update(&state, chunk, (size_t)r * 8);
}
libsha1_digest(&state, NULL, 0, hashsum);
+
+#if ALLOCA_LIMIT <= 0
+ free(chunk);
+#endif
return 0;
}
diff --git a/update.c b/update.c
index 1725eb8..8799061 100644
--- a/update.c
+++ b/update.c
@@ -21,7 +21,7 @@ libsha1_update(struct libsha1_state *restrict state, const void *restrict messag
if (off) {
n = msglen < sizeof(state->chunk) - off ? msglen : sizeof(state->chunk) - off;
- memcpy(state->chunk + off, message, n);
+ memcpy(&state->chunk[off], message, n);
if (off + n == sizeof(state->chunk))
libsha1_process(state, state->chunk);
message += n;