Re: Readline discards the last character of long messages

[Chet Ramey]

On 7/12/25 5:30 AM, Torgny Lyon wrote:

Bash Version: 5.3
Patch Level: 0
Release Status: maint

Description:
         When formatting long messages that wont fit into its buffer,
         readline will reallocate the buffer to be just as large as is
         needed, but it will then not make use of the whole buffer for
         the formatted message, resulting in the last character being
         left out. Fixing the call to vsnprintf() alone would fix the
         exhibited _behavior_.

         However, readline also decides to perform the reallocation of
         the buffer "too early". This explains why the bug is triggered
         already when the prompt in the example below is only 126
         characters. The 128 bytes of the buffer would be sufficient for
         holding the 126 characters of the prompt, a '/', and a
         terminating '\0', but readline is off by one and therefor
         performs the reallocation and the faulty formatting even in this
         case.

         The attached patch fixes both these issues.

Thanks for the report and patch.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    c...@case.edu    http://tiswww.cwru.edu/~chet/

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