88 lines
2.3 KiB
Diff
88 lines
2.3 KiB
Diff
diff -rup less-436-orig/filename.c less-436/filename.c
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--- less-436-orig/filename.c 2009-07-06 22:52:23.000000000 +0200
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+++ less-436/filename.c 2011-02-09 16:36:59.508940154 +0100
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@@ -843,6 +843,16 @@ open_altfile(filename, pf, pfd)
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#else
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lessopen++;
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returnfd = 1;
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+
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+ if (*lessopen == '|') {
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+ /*
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+ * If there is another vertical bar |, after
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+ * the first one, it indicates a "pipe preprocessor"
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+ * with correct exit status.
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+ */
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+ lessopen++;
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+ returnfd = 2;
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+ }
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#endif
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}
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if (*lessopen == '-') {
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@@ -879,17 +888,32 @@ open_altfile(filename, pf, pfd)
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*/
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f = fileno(fd);
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SET_BINARY(f);
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+ *pfd = (void *) fd;
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+ *pf = f;
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if (read(f, &c, 1) != 1)
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{
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/*
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- * Pipe is empty. This means there is no alt file.
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+ * Error or pipe is empty. Close it and eventually
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+ * check exit status of the pipe process.
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*/
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- pclose(fd);
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+ if (pclose(fd) == 0 && returnfd == 2) {
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+ /*
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+ * Exit status was zero, so the EOF was correct
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+ * empty output. Let the program open /dev/null
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+ * instead, as the pipe is already closed.
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+ * Set force_open to omit bad_file() check
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+ * failure, as it is special 'c' pseudo-device.
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+ */
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+ *pf = 0;
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+ *pfd = NULL;
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+ force_open = 1;
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+ return (save("/dev/null"));
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+ }
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+ *pf = 0;
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+ *pfd = NULL;
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return (NULL);
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}
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ch_ungetchar(c);
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- *pfd = (void *) fd;
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- *pf = f;
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return (save("-"));
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}
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#endif
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diff -rup less-436-orig/less.nro less-436/less.nro
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--- less-436-orig/less.nro 2011-02-09 16:00:12.520936431 +0100
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+++ less-436/less.nro 2011-02-09 16:30:33.161235986 +0100
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@@ -1147,11 +1147,26 @@ lesspipe.sh:
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.br
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;;
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.br
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+ *) exit 1
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+.br
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+ ;;
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+.br
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esac
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.br
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+ exit $?
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+.br
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.PP
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To use this script, put it where it can be executed and set
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LESSOPEN="|lesspipe.sh %s".
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+.PP
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+The script should return zero if the output was valid and non-zero
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+otherwise, so less could detect even a valid empty output
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+(for example while uncompressing gzipped empty file).
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+For backward-compatibility, this is not required by default. To turn
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+this functionality there should be another vertical bar (|) straight
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+after the first one in the LESSOPEN environment variable, eg.
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+LESSOPEN="||lesspipe.sh %s".
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+.PP
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When an input pipe is used, a LESSCLOSE postprocessor can be used,
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but it is usually not necessary since there is no replacement file
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to clean up.
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