1 #include "syshdrs.h"
2
3 #if !defined(NO_SIGNALS) && defined(SIGPIPE)
4 extern volatile Sjmp_buf gPipeJmp;
5 #endif
6
7 /* Read up to "size" bytes on sfd.
8 *
9 * If "retry" is on, after a successful read of less than "size"
10 * bytes, it will attempt to read more, upto "size."
11 *
12 * Although "retry" would seem to indicate you may want to always
13 * read "size" bytes or else it is an error, even with that on you
14 * may get back a value < size. Set "retry" to 0 when you want to
15 * return as soon as there is a chunk of data whose size is <= "size".
16 */
17
18 int
PRead(int sfd,char * const buf0,size_t size,int retry)19 PRead(int sfd, char *const buf0, size_t size, int retry)
20 {
21 int nread;
22 volatile int nleft;
23 char *volatile buf = buf0;
24 #if !defined(NO_SIGNALS) && defined(SIGPIPE)
25 vsio_sigproc_t sigpipe;
26
27 if (SSetjmp(gPipeJmp) != 0) {
28 (void) SSignal(SIGPIPE, (sio_sigproc_t) sigpipe);
29 nread = size - nleft;
30 if (nread > 0)
31 return (nread);
32 errno = EPIPE;
33 return (kBrokenPipeErr);
34 }
35
36 sigpipe = (vsio_sigproc_t) SSignal(SIGPIPE, SIOHandler);
37 #endif
38 errno = 0;
39
40 nleft = (int) size;
41 forever {
42 nread = read(sfd, buf, nleft);
43 if (nread <= 0) {
44 if (nread == 0) {
45 /* EOF */
46 nread = size - nleft;
47 goto done;
48 } else if (errno != EINTR) {
49 nread = size - nleft;
50 if (nread == 0)
51 nread = -1;
52 goto done;
53 } else {
54 errno = 0;
55 nread = 0;
56 /* Try again. */
57 }
58 }
59 nleft -= nread;
60 if ((nleft <= 0) || (retry == 0))
61 break;
62 buf += nread;
63 }
64 nread = size - nleft;
65
66 done:
67 #if !defined(NO_SIGNALS) && defined(SIGPIPE)
68 (void) SSignal(SIGPIPE, (sio_sigproc_t) sigpipe);
69 #endif
70 return (nread);
71 } /* PRead */
72