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Issue #379 - Fix read-line to be compatible with other I/O functions

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The function now uses the same port buffer as our other I/O functions.
This commit is contained in:
Justin Ethier 2021-07-14 23:00:42 -04:00
parent 215552cfe7
commit 71cca38b44
2 changed files with 14 additions and 34 deletions
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1
CHANGELOG.md
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@ -4,6 +4,7 @@
Bug Fixes
- Fix `read-line` to prevent data loss when used in conjunction with other I/O functions (such as `read-char`) to read from the same port. Previous versions of `read-line` would use a different internal buffer than our other I/O functions.
- Properly handle literal vectors at the top level of compiled code.
## 0.30.0 - July 2, 2021

47
runtime.c
View file

@ -7887,19 +7887,8 @@ object Cyc_io_read_u8(void *data, object cont, object port)
return Cyc_EOF;
}
// WIP - a version of read_line that uses our internal port buffer.
// This will be compatible with other I/O function such as read-char
//
// TODO: instead of fgets, read up to 1023 chars from our port buffer. per fgets,
// we stop when either (n-1) characters are read, the newline character is read,
// or the end-of-file is reached, whichever comes first
//
// other difference is we read one char at a time until final code point is completely read
//
// development in 2 phases:
// 1) build out so we can replace Cyc_io_read_line with this "slow" version, verifying everything works
// 2) integrate slow back into fast such that we can revert to this function if
// the buffer contains chars, else we use the fast read_line function
// A version of read_line that uses our internal port buffer for
// compatiblity with other I/O function such as read-char
object Cyc_io_read_line_slow(void *data, object cont, object port)
{
FILE *stream;
@ -7928,13 +7917,6 @@ object Cyc_io_read_line_slow(void *data, object cont, object port)
}
}
buf[i] = p->mem_buf[p->buf_idx++];
if (buf[i] == EOF) {
if (i == 0) { // Empty buffer, return EOF
return_thread_runnable_with_obj(data, Cyc_EOF, p);
} else {
break; // Handle buf contents below
}
}
if (buf[i] == '\n') {
break;
}
@ -7953,8 +7935,6 @@ object Cyc_io_read_line_slow(void *data, object cont, object port)
int rv = read_from_port(p);
if (!rv) {
break; // At EOF, return what we've got so far
// TODO: likely better to fall back to last fully-read codepoint.
// in that case we might still return EOF
}
}
c = p->mem_buf[p->buf_idx++];
@ -7983,13 +7963,10 @@ object Cyc_io_read_line_slow(void *data, object cont, object port)
return NULL;
}
/* TODO: this function needs some work, but approximates what is needed */
object Cyc_io_read_line(void *data, object cont, object port)
{
return Cyc_io_read_line_slow(data, cont, port);
}
/*
FILE *stream;
port_type *p;
char buf[1027];
int len, num_cp, i = 0;
char_type codepoint;
@ -8000,6 +7977,15 @@ object Cyc_io_read_line(void *data, object cont, object port)
if (stream == NULL) {
Cyc_rt_raise2(data, "Unable to read from closed port: ", port);
}
// If there is data in the port buffer we have to use the slow path
// for compatibility with other I/O functions
p = (port_type *)port;
if ( !(p->mem_buf_len == 0 || p->mem_buf_len == p->buf_idx)) {
return Cyc_io_read_line_slow(data, cont, port);
}
// Otherwise, the port buffer is empty so we can use the fast path below:
set_thread_blocked(data, cont);
errno = 0;
if (fgets(buf, 1023, stream) != NULL) {
@ -8031,17 +8017,10 @@ object Cyc_io_read_line(void *data, object cont, object port)
return_thread_runnable_with_obj(data, &s, port);
}
} else {
if (feof(stream)) {
return_thread_runnable_with_obj(data, Cyc_EOF, port);
} else {
// TODO: can't do this because we said thread could be blocked
//Cyc_rt_raise2(data, "Error reading from file: ", obj_int2obj(errno));
return_thread_runnable_with_obj(data, Cyc_EOF, port);
}
return_thread_runnable_with_obj(data, Cyc_EOF, port);
}
return NULL;
}
*/
/**
* @brief Read next token from the input port.