[SOLVED] Adding tags to header with rpmlib

Issue

I am trying to create a new header and insert some tags with the RPM Header API using the href="http://rpm.org/api/4.12.0.1/group__header.html#ga9a7cc53243734db48200933aecaea57c" rel="nofollow noreferrer">headerPut* functions, but in this simple example my attempted insertions fail with the exception of headerPutString and I am at a loss as to why:

Header s = NULL;
unsigned char md5[16] = {0};
uint32_t size = 42;

s = headerNew();

if (headerPutString(s, RPMSIGTAG_SHA1, "foo") != 1)
    fprintf(stderr, "headerPutString error\n");

if (headerPutUint32(s, RPMSIGTAG_SIZE, &size, 1) != 1)
    fprintf(stderr, "headerPutUint32 error\n");

if (headerPutBin(s, RPMSIGTAG_MD5, md5, 16) != 1)
    fprintf(stderr, "headerPutBin error\n");

Running this outputs:

headerPutUint32 error
headerPutBin error

and when I then call headerWrite and examine the resulting file contents with the hexdump tool, I can see that the header only contains the string-type tag.

Why can't I insert the other two?

Solution

Well, after some gdb debugging and looking through the RPM source files, I see where the problem is.

In the signature, RPMSIGTAG_SIZE (1000) is of type INT32 and RPMSIGTAG_MD5 (1004) is of type BIN. The problem is that these symbolic values also correspond to RPM header tags, where the type differs: RPMTAG_NAME is 1000 and is a STRING, RPMTAG_SUMMARY is 1004 and is an I18NSTRING. The RPM source files have no way to distinguish between the two and assume they are header tags, not signature tags.

Fortunately, the API also contains the headerPut function. This is actually what gets called by the type-specific functions after the sanity checks (including type checking), headerPut itself doesn't attempt any tag-type match, it just goes ahead and tries to add/append it, and is therefore a good solution for these situations.

Answered By - MC93

Answer Checked By - Marie Seifert (WPSolving Admin)