iBoot/platform/generic/breadcrumbs.c

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2023-07-08 13:03:17 -07:00
#include <lib/env.h>
#include <stdlib.h>
#include <lib/nvram.h>
#include <debug.h>
#include <platform.h>
#include <arch.h>
#define BREADCRUMB_BUFFER_SIZE 256 // This is arbitrarily sized, should be large enough for
// sensible options of key/value
#define BREADCRUMB_MIN_SIZE 3 // Smallest size of a breadcrumb
typedef struct {
char* buffer; // Storage for the breadcrumbs
int buffer_len; // Length of breadcrumb buffer
int wrpos; // Current write position
} breadcrumb_store_t;
static bool initialized = false;
breadcrumb_store_t breadcrumb_store;
static char* bc_cur_pos (void)
{
ASSERT(breadcrumb_store.wrpos <= breadcrumb_store.buffer_len);
return &breadcrumb_store.buffer[breadcrumb_store.wrpos];
}
static int bc_remaining (void)
{
ASSERT(breadcrumb_store.wrpos <= breadcrumb_store.buffer_len);
return breadcrumb_store.buffer_len - breadcrumb_store.wrpos;
}
void _platform_init_breadcrumbs_internal(void)
{
if (!initialized) {
breadcrumb_store.buffer = malloc(BREADCRUMB_BUFFER_SIZE);
breadcrumb_store.wrpos = 0;
breadcrumb_store.buffer_len = BREADCRUMB_BUFFER_SIZE;
initialized = (breadcrumb_store.buffer != NULL);
dprintf(DEBUG_INFO, "breadcrumb store initialized at %p\n", breadcrumb_store.buffer);
platform_record_breadcrumb_marker("BOOT");
}
}
void _platform_record_breadcrumb_internal(const char* key, const char* val)
{
if (initialized && bc_remaining() > BREADCRUMB_MIN_SIZE) {
int count = (int)snprintf(bc_cur_pos(), bc_remaining(), "%s=%s, ", key, val);
if (count > 0)
breadcrumb_store.wrpos += strlen(bc_cur_pos());
}
}
void _platform_record_breadcrumb_marker_internal(const char* val)
{
if (initialized && bc_remaining() > BREADCRUMB_MIN_SIZE) {
int count = (int)snprintf(bc_cur_pos(), bc_remaining(), "<%s> ", val);
if (count > 0)
breadcrumb_store.wrpos += strlen(bc_cur_pos());
}
}
void _platform_record_breadcrumb_int_internal(const char* key, int val)
{
if (initialized && bc_remaining() > BREADCRUMB_MIN_SIZE) {
int count = (int)snprintf(bc_cur_pos(), bc_remaining(), "%s=%d, ", key, val);
if (count > 0)
breadcrumb_store.wrpos += strlen(bc_cur_pos());
}
}
void _platform_commit_breadcrumbs_internal(const char* envvar)
{
if (initialized) {
platform_record_breadcrumb_marker("DONE");
// We expect this buffer to always be NULL terminated since it was built using
// snprintf(), but just to be sure, make sure the end of the buffer is terminated.
breadcrumb_store.buffer[breadcrumb_store.buffer_len - 1] = '\0';
const char* existing_breadcrumbs = env_get(envvar);
if (existing_breadcrumbs) {
dprintf(DEBUG_INFO, "Existing breadcrumbs found: '%s'\n", existing_breadcrumbs);
// If there's already iBoot breadcrumbs, we should preserve them chronologically
// (earliest first). Since we need to prepend, we might as well swap it with
// a new buffer.
if (bc_remaining() < (int)strlen(existing_breadcrumbs)) {
// Existing breadcrumbs would not fit. Drop the oldest breadcrumbs first
existing_breadcrumbs += ((int)strlen(existing_breadcrumbs) - bc_remaining());
}
char* tmp_buf = malloc(BREADCRUMB_BUFFER_SIZE);
if (tmp_buf) {
int count = snprintf(tmp_buf, BREADCRUMB_BUFFER_SIZE, "%s%s", existing_breadcrumbs, breadcrumb_store.buffer);
if (count >= 0 && count < BREADCRUMB_BUFFER_SIZE)
breadcrumb_store.wrpos = count;
else
breadcrumb_store.wrpos = 0;
free(breadcrumb_store.buffer);
breadcrumb_store.buffer = tmp_buf;
}
}
dprintf(DEBUG_INFO, "Committing breadcrumbs [used %d of %d bytes]: Setting '%s'='%s'\n", breadcrumb_store.wrpos, breadcrumb_store.buffer_len, envvar, breadcrumb_store.buffer);
env_set(envvar, breadcrumb_store.buffer, ENV_PERSISTENT);
nvram_save();
initialized=false; // Stop recording breadcrumbs and make redundant commits a no-op.
}
}