2010/9/3 Jilles Tjoelker :
> This patch assumes that the file descriptor is discarded afterwards (its
> position does not matter). Therefore the very common construct
> while read x; do
> ...
> done
> stops working.
Ohh.. thanks for that, I didn't see it.
Actually "while read x" continues to work.
But "reopening the file" doesn't as in :
read a b < datafile
echo ${a} ${b}
read a b < datafile
echo ${a} ${b}
I attached an updated patch that corrects this pb by discarding the
buffer when opening a new file.
I also put everything in new files (bufreadcmd.c & .h), in order to
ease its understanding.
--
Steve Schnepp
http://blog.pwkf.org/
>
> A possible fix is to check first if the input supports seeking. If it
> does, use the buffering and at the end of the line seek backwards for
> the number of bytes remaining in the buffer. If it does not, read one
> byte at a time.
>
> --
> Jilles Tjoelker
>
--
Steve Schnepp
http://blog.pwkf.org/
Common subdirectories: dash-0.5.4/src/bltin and dash-0.5.4-patched/src/bltin
diff -puN dash-0.5.4/src/bufreadcmd.c dash-0.5.4-patched/src/bufreadcmd.c
--- dash-0.5.4/src/bufreadcmd.c 1970-01-01 01:00:00.0 +0100
+++ dash-0.5.4-patched/src/bufreadcmd.c 2010-09-04 12:31:46.0 +0200
@@ -0,0 +1,59 @@
+/*
+ * Offers a buffered read builtin
+ */
+
+#include
+#include
+
+#include "bufreadcmd.h"
+
+#ifdef BUF_READ_BUILTIN_DISABLED
+int dup2_wrapper(int old, int new) {
+ return dup2(old, new);
+}
+int read_stdin_bufferred(char *c) {
+ return read(0, buffer, 1);
+}
+#else // BUF_READ_BUILTIN_DISABLED
+
+/*
+ * Reads from fd 0, with a CHUNK_READ_SIZE,
+ * but emitting one char at a time
+ */
+#define CHUNK_READ_SIZE 32
+static char buffer[CHUNK_READ_SIZE];
+static int buffer_offset = 0;
+static int buffer_len = 0;
+
+int read_stdin_bufferred(char* c) {
+ if (buffer_len == 0) {
+ // No caracter left, resetting buffer & read some more
+ buffer_offset = 0;
+ buffer_len = read(0, buffer, CHUNK_READ_SIZE);
+
+ if (buffer_len == 0) {
+ // Nothing to read anymore
+ return 0;
+ }
+ }
+
+ // Still some character left
+ *c = buffer[buffer_offset++];
+ buffer_len--;
+
+ return 1;
+}
+
+static void _flush_readcmd(int fd) {
+ if (fd == 0) {
+ // Flush the buffer, discarding its content
+ buffer_len = 0;
+ }
+}
+
+/* Intercept dup2() calls */
+int dup2_wrapper(int old, int new) {
+ _flush_readcmd(new);
+ return dup2(old, new);
+}
+#endif // BUF_READ_BUILTIN_DISABLED
diff -puN dash-0.5.4/src/bufreadcmd.h dash-0.5.4-patched/src/bufreadcmd.h
--- dash-0.5.4/src/bufreadcmd.h 1970-01-01 01:00:00.0 +0100
+++ dash-0.5.4-patched/src/bufreadcmd.h 2010-09-04 12:23:53.0 +0200
@@ -0,0 +1,3 @@
+/* Used for flushing the readcmd read() buffer */
+int dup2_wrapper(int to, int from);
+int read_stdin_bufferred(char *c);
Common subdirectories: dash-0.5.4/src/.deps and dash-0.5.4-patched/src/.deps
diff -puN dash-0.5.4/src/eval.c dash-0.5.4-patched/src/eval.c
--- dash-0.5.4/src/eval.c 2007-07-13 10:26:42.0 +0200
+++ dash-0.5.4-patched/src/eval.c 2010-09-04 12:24:55.0 +0200
@@ -64,6 +64,8 @@
#include "myhistedit.h"
#endif
+#include "bufreadcmd.h"
+
/* flags in argument to evaltree */
#define EV_EXIT 01 /* exit after evaluating tree */
@@ -543,11 +545,12 @@ evalpipe(union node *n, int flags)
close(pip[0]);
}
if (prevfd > 0) {
-dup2(prevfd, 0);
+dup2_wrapper(prevfd, 0);
+
close(prevfd);
}
if (pip[1] > 1) {
-dup2(pip[1], 1);
+dup2_wrapper(pip[1], 1);
close(pip[1]);
}
evaltreenr(lp->n, flags);
@@ -625,7 +628,7 @@ evalbackcmd(union node *n, struct backcm
FORCEINTON;
close(pip[0]);
if (pip[1] != 1) {
-dup2(pip[1], 1);
+dup2_wrapper(pip[1], 1);
close(pip[1]);
}
eflag = 0;
diff -puN dash-0.5.4/src/Makefile dash-0.5.4-patched/src/Makefile
--- dash-0.5.4/src/Makefile 2010-09-04 13:06:05.0 +0200
+++ dash-0.5.4-patched/src/Makefile 2010-09-04 13:08:26.0 +0200
@@ -57,7 +57,7 @@ am__objects_1 = alias.$(OBJEXT) arith_yy
miscbltin.$(OBJEXT) mystring.$(OBJEXT) options.$(OBJEXT) \
parser.$(OBJEXT) redir.$(OBJEXT) show.$(OBJEXT) trap.$(OBJEXT) \
output.$(OBJEXT) printf.$(OBJEXT) system.$(OBJEXT) \
- test.$(OBJEXT) times.$(OBJEXT) var.$(OBJEXT)
+ test.$(OBJEXT) times.$(OBJEXT) var.$(OBJEXT) bufreadcmd.$(OBJEXT)
am_dash_OBJECTS = $(am__objects_1) arith.$(OBJEXT)
dash_OBJECTS = $(am_dash_OBJECTS)
dash_DEPENDENCIES = builtins.o init.o nodes.o signames.o syntax.o
@@ -169,14 +169,14 @@ dash_CFILES = \
alias.c arith_yylex.c cd.c error.c eval.c exec.c expand.c \
histedit.c input.c jobs.c mail.c main.c memalloc.c miscbltin.c \
mystring.c options.c parser.c redir.c show.c trap.c output.c \
-
