[libvirt] [PATCH 1/2] virCommand: document behavior on no output

Option 1: This patch (all callers have to worry about NULL buffers, but checking for output is a simple pointer check). Option 2: Guarantee that outbuf/errbuf are allocated, even if to the empty string. Caller always has to free the result, and empty output check requires checking if *outbuf=='\0'. Personally, I prefer option 2. Thoughts? * docs/internals/command.html.in: Update documentation. * src/util/command.c (virCommandSetOutputBuffer) (virCommandSetErrorBuffer) Guarantee NULL buffer on no output. --- docs/internals/command.html.in | 4 ++-- src/util/command.c | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/docs/internals/command.html.in b/docs/internals/command.html.in index c4fa800..ea9ec64 100644 --- a/docs/internals/command.html.in +++ b/docs/internals/command.html.in @@ -349,8 +349,8 @@ <p> Once the command has finished executing, these buffers - will contain the output. It is the callers responsibility - to free these buffers. + will contain the output, or be NULL if there was no output. It + is the callers responsibility to free these buffers. </p> <h3><a name="directory">Setting working directory</a></h3> diff --git a/src/util/command.c b/src/util/command.c index aa43f76..1923799 100644 --- a/src/util/command.c +++ b/src/util/command.c @@ -549,6 +549,7 @@ virCommandSetOutputBuffer(virCommandPtr cmd, char **outbuf) return; } + VIR_FREE(*outbuf); cmd->outbuf = outbuf; cmd->outfdptr = &cmd->outfd; } @@ -569,6 +570,7 @@ virCommandSetErrorBuffer(virCommandPtr cmd, char **errbuf) return; } + VIR_FREE(*errbuf); cmd->errbuf = errbuf; cmd->errfdptr = &cmd->errfd; } -- 1.7.3.2