Factor out code to read mailboxes, and make read more robust

[empserver] / src / lib / common / mailbox.c

diff --git a/src/lib/common/mailbox.c b/src/lib/common/mailbox.c
index b317a95e18947e08765d960a1ece1ad21cdfe290..f940cad01a64beb8a2b05c80b7d48f494873c32c 100644 (file)
--- a/src/lib/common/mailbox.c
+++ b/src/lib/common/mailbox.c
@@ -36,6 +36,7 @@
 #include <stdio.h>
 #include "optlist.h"
 #include "tel.h"
+#include "prototypes.h"
 
 char *
 mailbox(char *buf, natid cn)
@@ -43,3 +44,57 @@ mailbox(char *buf, natid cn)
     sprintf(buf, "%s/tel%d", teldir, cn);
     return buf;
 }
+
+/*
+ * Read telegram header from FP into TEL.
+ * MBOX is the file name, it is used for logging errors.
+ * Return 1 on success, 0 on EOF, -1 on error.
+ */
+int
+tel_read_header(FILE *fp, char *mbox, struct telstr *tel)
+{
+    size_t n;
+
+    n = fread(tel, 1, sizeof(*tel), fp);
+    if (n == 0 && feof(fp))
+       return 0;
+    if (n != sizeof(*tel)
+       || tel->tel_type > TEL_LAST || tel->tel_from > MAXNOC) {
+       logerror("Mailbox %s corrupt: bad header", mbox);
+       return -1;
+    }
+    return 1;
+}
+
+/*
+ * Read telegram body from FP.
+ * MBOX is the file name, it is used for logging errors.
+ * TEL is the header.
+ * Unless SINK is null, it is called like SINK(CHUNK, SZ, ARG) to
+ * consume the body, chunk by chunk.  The chunks are UTF-8, and
+ * CHUNK[SZ} is 0.  Reading fails when SINK() returns a negative
+ * value.
+ * Return 0 on success, -1 on failure.
+ */
+int
+tel_read_body(FILE *fp, char *mbox, struct telstr *tel,
+             int (*sink)(char *, size_t, void *),
+             void *arg)
+{
+    char buf[4096];
+    size_t left, sz;
+
+    left = tel->tel_length;
+    while (left) {
+       sz = MIN(left, sizeof(buf) - 1);
+       if (fread(buf, 1, sz, fp) != sz) {
+           logerror("Mailbox %s corrupt: can't read body", mbox);
+           return -1;
+       }
+       buf[sz] = 0;
+       if (sink && sink(buf, sz, arg) < 0)
+           return -1;
+       left -= sz;
+    }
+    return 0;
+}