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    Subject[PATCH 09/33] Adding notes infrastructure
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    Date
    Creating Elf_note structure and adding the required functions to add the notes.

    Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
    Signed-off-by: Janani Venkataraman <jananive@linux.vnet.ibm.com>
    ---
    src/coredump.c | 15 ++++++++++++
    src/coredump.h | 13 ++++++++++
    src/elf.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    src/elf32.c | 1 +
    src/elf64.c | 1 +
    5 files changed, 103 insertions(+)

    diff --git a/src/coredump.c b/src/coredump.c
    index de0a7ce..0fd6343e 100644
    --- a/src/coredump.c
    +++ b/src/coredump.c
    @@ -166,6 +166,18 @@ int release_threads(void)
    return ret;
    }

    +/* Free Notes */
    +void free_notes(struct mem_note *head)
    +{
    + struct mem_note *tmp;
    +
    + while (head) {
    + tmp = head->next;
    + free(head);
    + head = tmp;
    + }
    +}
    +
    /* Performs the core dump */
    int do_coredump(int pid, char *core_file)
    {
    @@ -216,6 +228,9 @@ cleanup:
    if (cp.elf_hdr)
    free(cp.elf_hdr);

    + if (cp.notes)
    + free_notes(cp.notes);
    +
    errno = status;

    return ret;
    diff --git a/src/coredump.h b/src/coredump.h
    index 4e508c1..9b19f19 100644
    --- a/src/coredump.h
    +++ b/src/coredump.h
    @@ -25,6 +25,18 @@ struct maps {
    char fname[0];
    };

    +/*
    + * Structure for Notes
    + * We follow this linked list data-type as we dont know the number of notes
    + * as that depends on the architecture. Also the notebuf contains the final
    + * in-file format for the note data.
    + */
    +struct mem_note {
    + unsigned char *notebuf; /* Notes - type, name_sz, datasz, name and data */
    + unsigned int size; /* Size of Note */
    + struct mem_note *next;
    +};
    +
    /* Structure for the Core of the Process */
    struct core_proc {
    int thread_count; /* Number of threads */
    @@ -33,4 +45,5 @@ struct core_proc {
    int phdrs_count; /* Number of Program headers */
    int elf_class; /* Elf class of the process */
    void *elf_hdr; /* Stores the ELF_header */
    + struct mem_note *notes; /* Head of Notes */
    };
    diff --git a/src/elf.c b/src/elf.c
    index 9f65c77..dfcb1d7 100644
    --- a/src/elf.c
    +++ b/src/elf.c
    @@ -30,6 +30,79 @@
    #include <linux/elf.h>
    #include "coredump.h"

    +#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
    +
    +/* Appending the note to the list */
    +static void append_note(struct mem_note *new_note, struct core_proc *cp)
    +{
    + struct mem_note *tmp;
    +
    + if (cp->notes == NULL)
    + cp->notes = new_note;
    + else {
    + tmp = cp->notes;
    + while (tmp->next != NULL)
    + tmp = tmp->next;
    + tmp->next = new_note;
    + }
    +}
    +
    +/* Adding a new note */
    +static int add_note(const char *name, int type, unsigned int data_sz, void *data,
    + struct core_proc *cp)
    +{
    + unsigned char *ptr, *notebuf;
    + unsigned int namelen, size, data_offset;
    + Elf_Nhdr *note;
    + struct mem_note *tmp = malloc(sizeof(struct mem_note));
    + if (!tmp) {
    + status = errno;
    + gencore_log("Failure in adding note.\n");
    + return -1;
    + }
    +
    + /* Calculate the size of the Notes */
    + namelen = strlen(name) + 1;
    + size = sizeof(Elf_Nhdr);
    + size += namelen;
    +
    + /* Note down the offset where data is to be stored */
    + data_offset = size = roundup(size, 4);
    + size += data_sz;
    + size = roundup(size, 4);
    +
    + /* Allocate the required size, initialized to 0 */
    + notebuf = calloc(1, size);
    + if (!notebuf) {
    + status = errno;
    + gencore_log("Could not allocate memory for Notes buffer.\n");
    + return -1;
    + }
    +
    + note = (Elf_Nhdr *)notebuf;
    +
    + /* Where name should be stored */
    + ptr = (unsigned char *) (note + 1);
    +
    + note->n_type = type;
    + note->n_namesz = strlen(name) + 1;
    + note->n_descsz = data_sz;
    +
    + /* Store name */
    + memcpy(ptr, name, namelen);
    +
    + /* Store data */
    + memcpy(notebuf + data_offset, data, data_sz);
    +
    + tmp->notebuf = notebuf;
    + tmp->size = size;
    + tmp->next = NULL;
    +
    + append_note(tmp, cp);
    +
    + return 0;
    +}
    +
    /* Fetchs ELF header of the executable */
    static int get_elf_hdr_exe_file(int pid, Elf_Ehdr *elf)
    {
    diff --git a/src/elf32.c b/src/elf32.c
    index 1a95ff2..01b3923 100644
    --- a/src/elf32.c
    +++ b/src/elf32.c
    @@ -33,5 +33,6 @@
    #define Elf_Ehdr Elf32_Ehdr
    #define Elf_Phdr Elf32_Phdr
    #define Elf_Shdr Elf32_Shdr
    +#define Elf_Nhdr Elf32_Nhdr

    #include "elf.c"
    diff --git a/src/elf64.c b/src/elf64.c
    index 953b826..a99a73b 100644
    --- a/src/elf64.c
    +++ b/src/elf64.c
    @@ -33,5 +33,6 @@
    #define Elf_Ehdr Elf64_Ehdr
    #define Elf_Phdr Elf64_Phdr
    #define Elf_Shdr Elf64_Shdr
    +#define Elf_Nhdr Elf64_Nhdr

    #include "elf.c"


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