diff options
Diffstat (limited to 'winsup/cygwin/socket_tests/lib/read_line.c')
-rw-r--r-- | winsup/cygwin/socket_tests/lib/read_line.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/winsup/cygwin/socket_tests/lib/read_line.c b/winsup/cygwin/socket_tests/lib/read_line.c new file mode 100644 index 000000000..f6c5f96c1 --- /dev/null +++ b/winsup/cygwin/socket_tests/lib/read_line.c @@ -0,0 +1,73 @@ +/*************************************************************************\ +* Copyright (C) Michael Kerrisk, 2018. * +* * +* This program is free software. You may use, modify, and redistribute it * +* under the terms of the GNU Lesser General Public License as published * +* by the Free Software Foundation, either version 3 or (at your option) * +* any later version. This program is distributed without any warranty. * +* See the files COPYING.lgpl-v3 and COPYING.gpl-v3 for details. * +\*************************************************************************/ + +/* Listing 59-1 */ + +/* read_line.c + + Implementation of readLine(). +*/ +#include <unistd.h> +#include <errno.h> +#include "read_line.h" /* Declaration of readLine() */ + +/* Read characters from 'fd' until a newline is encountered. If a newline + character is not encountered in the first (n - 1) bytes, then the excess + characters are discarded. The returned string placed in 'buf' is + null-terminated and includes the newline character if it was read in the + first (n - 1) bytes. The function return value is the number of bytes + placed in buffer (which includes the newline character if encountered, + but excludes the terminating null byte). */ + +ssize_t +readLine(int fd, void *buffer, size_t n) +{ + ssize_t numRead; /* # of bytes fetched by last read() */ + size_t totRead; /* Total bytes read so far */ + char *buf; + char ch; + + if (n <= 0 || buffer == NULL) { + errno = EINVAL; + return -1; + } + + buf = buffer; /* No pointer arithmetic on "void *" */ + + totRead = 0; + for (;;) { + numRead = read(fd, &ch, 1); + + if (numRead == -1) { + if (errno == EINTR) /* Interrupted --> restart read() */ + continue; + else + return -1; /* Some other error */ + + } else if (numRead == 0) { /* EOF */ + if (totRead == 0) /* No bytes read; return 0 */ + return 0; + else /* Some bytes read; add '\0' */ + break; + + } else { /* 'numRead' must be 1 if we get here */ + if (totRead < n - 1) { /* Discard > (n - 1) bytes */ + totRead++; + *buf++ = ch; + } + + if (ch == '\n') + break; + } + } + + *buf = '\0'; + return totRead; +} |