From dccb33ab0c33a1d90c4f4bba7b276b4fad0e286a Mon Sep 17 00:00:00 2001
From: Pablo Curiel <pabloacurielz@gmail.com>
Date: Fri, 24 Apr 2020 14:42:16 -0400
Subject: [PATCH] PFS0 read improved.

---
 source/main.c | 18 ++++--------------
 source/pfs0.c | 28 ++++++++++++++++++++++++----
 source/pfs0.h | 10 +++-------
 3 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/source/main.c b/source/main.c
index 6f00495..7d646f8 100644
--- a/source/main.c
+++ b/source/main.c
@@ -220,32 +220,22 @@ int main(int argc, char *argv[])
     printf("pfs0 get entry by name succeeded\n");
     consoleUpdate(NULL);
     
-    u64 main_npdm_offset = 0;
-    if (!pfs0GetEntryDataOffset(&pfs0_ctx, pfs0_entry, &main_npdm_offset))
-    {
-        printf("pfs0 get entry data offset failed\n");
-        goto out2;
-    }
-    
-    printf("main.npdm offset = 0x%lX\n", main_npdm_offset);
-    consoleUpdate(NULL);
-    
     tmp_file = fopen("sdmc:/nxdt_test/main.npdm", "wb");
     if (tmp_file)
     {
         u64 blksize = 0x400000;
         u64 total = pfs0_entry->size;
         
-        printf("main.npdm created: 0x%lX\n", total);
+        printf("main.npdm created. Target size -> 0x%lX\n", total);
         consoleUpdate(NULL);
         
         for(u64 curpos = 0; curpos < total; curpos += blksize)
         {
             if (blksize > (total - curpos)) blksize = (total - curpos);
             
-            if (!ncaReadFsSection(pfs0_ctx.nca_fs_ctx, buf, blksize, main_npdm_offset + curpos))
+            if (!pfs0ReadEntryData(&pfs0_ctx, pfs0_entry, buf, blksize, 0))
             {
-                printf("nca read section failed\n");
+                printf("pfs0 read entry data failed\n");
                 goto out2;
             }
             
@@ -255,7 +245,7 @@ int main(int argc, char *argv[])
         fclose(tmp_file);
         tmp_file = NULL;
         
-        printf("nca read main.npdm success\n");
+        printf("pfs0 read main.npdm success\n");
     } else {
         printf("main.npdm not created\n");
     }
diff --git a/source/pfs0.c b/source/pfs0.c
index 8a1eea1..d4efc2b 100644
--- a/source/pfs0.c
+++ b/source/pfs0.c
@@ -58,8 +58,6 @@ bool pfs0InitializeContext(PartitionFileSystemContext *out, NcaFsSectionContext
     /* Read partial PFS0 header */
     u32 magic = 0;
     PartitionFileSystemHeader pfs0_header = {0};
-    
-    u64 main_npdm_offset = 0;
     PartitionFileSystemEntry *main_npdm_entry = NULL;
     
     if (!ncaReadFsSection(nca_fs_ctx, &pfs0_header, sizeof(PartitionFileSystemHeader), out->offset))
@@ -100,8 +98,30 @@ bool pfs0InitializeContext(PartitionFileSystemContext *out, NcaFsSectionContext
     }
     
     /* Check if we're dealing with an ExeFS section */
-    if ((main_npdm_entry = pfs0GetEntryByName(out, "main.npdm")) != NULL && pfs0GetEntryDataOffset(out, main_npdm_entry, &main_npdm_offset) && \
-        ncaReadFsSection(out->nca_fs_ctx, &magic, sizeof(u32), main_npdm_offset) && __builtin_bswap32(magic) == NPDM_META_MAGIC) out->is_exefs = true;
+    if ((main_npdm_entry = pfs0GetEntryByName(out, "main.npdm")) != NULL && pfs0ReadEntryData(out, main_npdm_entry, &magic, sizeof(u32), 0) && \
+        __builtin_bswap32(magic) == NPDM_META_MAGIC) out->is_exefs = true;
+    
+    return true;
+}
+
+bool pfs0ReadEntryData(PartitionFileSystemContext *ctx, PartitionFileSystemEntry *fs_entry, void *out, u64 read_size, u64 offset)
+{
+    if (!ctx || !ctx->nca_fs_ctx || !ctx->hash_info || !ctx->size || !ctx->header_size || !ctx->header || !fs_entry || fs_entry->offset >= ctx->size || \
+        (fs_entry->offset + fs_entry->size) > ctx->size || !out || !read_size || offset >= fs_entry->size || (offset + read_size) > fs_entry->size)
+    {
+        LOGFILE("Invalid parameters!");
+        return false;
+    }
+    
+    /* Calculate offset relative to the start of the NCA FS section */
+    u64 section_offset = (ctx->offset + ctx->header_size + fs_entry->offset + offset);
+    
+    /* Read entry data */
+    if (!ncaReadFsSection(ctx->nca_fs_ctx, out, read_size, section_offset))
+    {
+        LOGFILE("Failed to read PFS0 entry data!");
+        return false;
+    }
     
     return true;
 }
diff --git a/source/pfs0.h b/source/pfs0.h
index 7470ee7..e0cd171 100644
--- a/source/pfs0.h
+++ b/source/pfs0.h
@@ -59,6 +59,9 @@ static inline void pfs0FreeContext(PartitionFileSystemContext *ctx)
     memset(ctx, 0, sizeof(PartitionFileSystemContext));
 }
 
+/// Reads data from a previously retrieved PartitionFileSystemEntry using a PFS0 context.
+bool pfs0ReadEntryData(PartitionFileSystemContext *ctx, PartitionFileSystemEntry *fs_entry, void *out, u64 read_size, u64 offset);
+
 /// Miscellaneous functions.
 
 static inline u32 pfs0GetEntryCount(PartitionFileSystemContext *ctx)
@@ -67,13 +70,6 @@ static inline u32 pfs0GetEntryCount(PartitionFileSystemContext *ctx)
     return ((PartitionFileSystemHeader*)ctx->header)->entry_count;
 }
 
-static inline bool pfs0GetEntryDataOffset(PartitionFileSystemContext *ctx, PartitionFileSystemEntry *fs_entry, u64 *out_offset)
-{
-    if (!ctx || !ctx->header_size || !ctx->header || !fs_entry || !out_offset) return false;
-    *out_offset = (ctx->offset + ctx->header_size + fs_entry->offset);  /* Relative to the start of the NCA FS section */
-    return true;
-}
-
 static inline PartitionFileSystemEntry *pfs0GetEntryByIndex(PartitionFileSystemContext *ctx, u32 idx)
 {
     if (idx >= pfs0GetEntryCount(ctx)) return NULL;