pg: command enters infinite loop
In a multibyte locale such as en_GB.UTF-8, the pg command cannot handle files containing a form feed character (ASCII 0x0c) at the start of a line. The program enters an infinite loop. I've traced the problem to the function endline_for_mb in file pg.c. The code assumes that the libc function wcwidth will return a nonnegative value, which is not true for a form feed character. wcwidth returns -1 and the unsigned variable "pos" goes into underflow. I'll attach a patch which tests whether the character is printable before calling wcwidth. If not, it uses instead the width of the constant L'?' which is later used to replace nonprintable characters. I trust that we can assume printability of this constant :-) Steps to Reproduce: 1. Select a multibyte locale (tested with en_GB.UTF-8) 2. Create a file with a form feed character (0x0c) at the start of a line. 3. Try to display this file using the pg command. Reported-by: Mark Calderbank <m.calderbank@iname.com> Reported-by: Mike Frysinger <vapier@gentoo.org> Addresses: https://bugs.gentoo.org/297717 Signed-off-by: Karel Zak <kzak@redhat.com>
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@ -448,7 +448,10 @@ endline_for_mb(unsigned col, char *s)
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pos += TABSIZE - (pos % TABSIZE);
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break;
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default:
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pos += wcwidth(*p);
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if (iswprint(*p))
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pos += wcwidth(*p);
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else
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pos += wcwidth(L'?');
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}
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if (pos > col) {
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if (*p == L'\t')
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