fix some more invalid unsafe code

More cases similar to those identified in #23914
fix #33899

(cherry picked from commit e1086fe)

Author: vtjnash

base/stream.jl

@@ -917,7 +917,7 @@ function readuntil(x::LibuvStream, c::UInt8; keep::Bool=false)
     return bytes
 end
 
-uv_write(s::LibuvStream, p::Vector{UInt8}) = uv_write(s, pointer(p), UInt(sizeof(p)))
+uv_write(s::LibuvStream, p::Vector{UInt8}) = GC.@preserve p uv_write(s, pointer(p), UInt(sizeof(p)))
 
 # caller must have acquired the iolock
 function uv_write(s::LibuvStream, p::Ptr{UInt8}, n::UInt)

base/strings/search.jl

@@ -34,8 +34,8 @@ function _search(a::Union{String,ByteArray}, b::Union{Int8,UInt8}, i::Integer =
         return i == n+1 ? 0 : throw(BoundsError(a, i))
     end
     p = pointer(a)
-    q = ccall(:memchr, Ptr{UInt8}, (Ptr{UInt8}, Int32, Csize_t), p+i-1, b, n-i+1)
-    q == C_NULL ? 0 : Int(q-p+1)
+    q = GC.@preserve a ccall(:memchr, Ptr{UInt8}, (Ptr{UInt8}, Int32, Csize_t), p+i-1, b, n-i+1)
+    return q == C_NULL ? 0 : Int(q-p+1)
 end
 
 function _search(a::ByteArray, b::AbstractChar, i::Integer = 1)
@@ -74,8 +74,8 @@ function _rsearch(a::Union{String,ByteArray}, b::Union{Int8,UInt8}, i::Integer =
         return i == n+1 ? 0 : throw(BoundsError(a, i))
     end
     p = pointer(a)
-    q = ccall(:memrchr, Ptr{UInt8}, (Ptr{UInt8}, Int32, Csize_t), p, b, i)
-    q == C_NULL ? 0 : Int(q-p+1)
+    q = GC.@preserve a ccall(:memrchr, Ptr{UInt8}, (Ptr{UInt8}, Int32, Csize_t), p, b, i)
+    return q == C_NULL ? 0 : Int(q-p+1)
 end
 
 function _rsearch(a::ByteArray, b::AbstractChar, i::Integer = length(a))

base/strings/string.jl

@@ -87,7 +87,8 @@ codeunit(s::String) = UInt8
 
 @inline function codeunit(s::String, i::Integer)
     @boundscheck checkbounds(s, i)
-    GC.@preserve s unsafe_load(pointer(s, i))
+    b = GC.@preserve s unsafe_load(pointer(s, i))
+    return b
 end
 
 ## comparison ##
@@ -112,7 +113,7 @@ typemin(::String) = typemin(String)
 
 ## thisind, nextind ##
 
-Base.@propagate_inbounds thisind(s::String, i::Int) = _thisind_str(s, i)
+@propagate_inbounds thisind(s::String, i::Int) = _thisind_str(s, i)
 
 # s should be String or SubString{String}
 @inline function _thisind_str(s, i::Int)
@@ -133,7 +134,7 @@ Base.@propagate_inbounds thisind(s::String, i::Int) = _thisind_str(s, i)
     return i
 end
 
-Base.@propagate_inbounds nextind(s::String, i::Int) = _nextind_str(s, i)
+@propagate_inbounds nextind(s::String, i::Int) = _nextind_str(s, i)
 
 # s should be String or SubString{String}
 @inline function _nextind_str(s, i::Int)
@@ -251,7 +252,7 @@ getindex(s::String, r::UnitRange{<:Integer}) = s[Int(first(r)):Int(last(r))]
     j = nextind(s, j) - 1
     n = j - i + 1
     ss = _string_n(n)
-    unsafe_copyto!(pointer(ss), pointer(s, i), n)
+    GC.@preserve s ss unsafe_copyto!(pointer(ss), pointer(s, i), n)
     return ss
 end
 
@@ -323,7 +324,7 @@ function repeat(c::Char, r::Integer)
     n = 4 - (leading_zeros(u | 0xff) >> 3)
     s = _string_n(n*r)
     p = pointer(s)
-    if n == 1
+    GC.@preserve s if n == 1
         ccall(:memset, Ptr{Cvoid}, (Ptr{UInt8}, Cint, Csize_t), p, u % UInt8, r)
     elseif n == 2
         p16 = reinterpret(Ptr{UInt16}, p)
@@ -340,7 +341,7 @@ function repeat(c::Char, r::Integer)
             unsafe_store!(p, b3, 3i + 3)
         end
     elseif n == 4
-        p32 = reinterpret(Ptr{UInt32}, pointer(s))
+        p32 = reinterpret(Ptr{UInt32}, p)
         for i = 1:r
             unsafe_store!(p32, u, i)
         end
@@ -349,11 +350,11 @@ function repeat(c::Char, r::Integer)
 end
 
 function filter(f, s::String)
-    out = Base.StringVector(sizeof(s))
+    out = StringVector(sizeof(s))
     offset = 1
     for c in s
         if f(c)
-            offset += Base.__unsafe_string!(out, c, offset)
+            offset += __unsafe_string!(out, c, offset)
         end
     end
     resize!(out, offset-1)

base/strings/substring.jl

@@ -51,7 +51,11 @@ convert(::Type{SubString{S}}, s::AbstractString) where {S<:AbstractString} =
     SubString(convert(S, s))
 convert(::Type{T}, s::T) where {T<:SubString} = s
 
-String(s::SubString{String}) = unsafe_string(pointer(s.string, s.offset+1), s.ncodeunits)
+function String(s::SubString{String})
+    parent = s.string
+    copy = GC.@preserve parent unsafe_string(pointer(parent, s.offset+1), s.ncodeunits)
+    return copy
+end
 
 ncodeunits(s::SubString) = s.ncodeunits
 codeunit(s::SubString) = codeunit(s.string)
@@ -151,25 +155,27 @@ end
 string(a::String)            = String(a)
 string(a::SubString{String}) = String(a)
 
-@inline function __unsafe_string!(out, c::Char, offs::Integer)
+@inline function __unsafe_string!(out, c::Char, offs::Integer) # out is a (new) String (or StringVector)
     x = bswap(reinterpret(UInt32, c))
     n = ncodeunits(c)
-    unsafe_store!(pointer(out, offs), x % UInt8)
-    n == 1 && return n
-    x >>= 8
-    unsafe_store!(pointer(out, offs+1), x % UInt8)
-    n == 2 && return n
-    x >>= 8
-    unsafe_store!(pointer(out, offs+2), x % UInt8)
-    n == 3 && return n
-    x >>= 8
-    unsafe_store!(pointer(out, offs+3), x % UInt8)
+    GC.@preserve out begin
+        unsafe_store!(pointer(out, offs), x % UInt8)
+        n == 1 && return n
+        x >>= 8
+        unsafe_store!(pointer(out, offs+1), x % UInt8)
+        n == 2 && return n
+        x >>= 8
+        unsafe_store!(pointer(out, offs+2), x % UInt8)
+        n == 3 && return n
+        x >>= 8
+        unsafe_store!(pointer(out, offs+3), x % UInt8)
+    end
     return n
 end
 
 @inline function __unsafe_string!(out, s::Union{String, SubString{String}}, offs::Integer)
     n = sizeof(s)
-    unsafe_copyto!(pointer(out, offs), pointer(s), n)
+    GC.@preserve s out unsafe_copyto!(pointer(out, offs), pointer(s), n)
     return n
 end
 
@@ -200,7 +206,7 @@ function repeat(s::Union{String, SubString{String}}, r::Integer)
         ccall(:memset, Ptr{Cvoid}, (Ptr{UInt8}, Cint, Csize_t), out, b, r)
     else
         for i = 0:r-1
-            unsafe_copyto!(pointer(out, i*n+1), pointer(s), n)
+            GC.@preserve s out unsafe_copyto!(pointer(out, i*n+1), pointer(s), n)
         end
     end
     return out

base/strings/util.jl

@@ -442,7 +442,7 @@ function replace(str::String, pat_repl::Pair; count::Integer=typemax(Int))
     out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)))
     while j != 0
         if i == a || i <= k
-            unsafe_write(out, pointer(str, i), UInt(j-i))
+            GC.@preserve str unsafe_write(out, pointer(str, i), UInt(j-i))
             _replace(out, repl, str, r, pattern)
         end
         if k < j